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788 lines
20 KiB
788 lines
20 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright (C) 2008-2014 Mathieu Desnoyers |
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*/ |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/types.h> |
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#include <linux/jhash.h> |
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#include <linux/list.h> |
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#include <linux/rcupdate.h> |
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#include <linux/tracepoint.h> |
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#include <linux/err.h> |
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#include <linux/slab.h> |
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#include <linux/sched/signal.h> |
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#include <linux/sched/task.h> |
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#include <linux/static_key.h> |
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|
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enum tp_func_state { |
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TP_FUNC_0, |
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TP_FUNC_1, |
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TP_FUNC_2, |
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TP_FUNC_N, |
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}; |
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extern tracepoint_ptr_t __start___tracepoints_ptrs[]; |
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extern tracepoint_ptr_t __stop___tracepoints_ptrs[]; |
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DEFINE_SRCU(tracepoint_srcu); |
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EXPORT_SYMBOL_GPL(tracepoint_srcu); |
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enum tp_transition_sync { |
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TP_TRANSITION_SYNC_1_0_1, |
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TP_TRANSITION_SYNC_N_2_1, |
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_NR_TP_TRANSITION_SYNC, |
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}; |
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struct tp_transition_snapshot { |
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unsigned long rcu; |
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unsigned long srcu; |
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bool ongoing; |
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}; |
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/* Protected by tracepoints_mutex */ |
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static struct tp_transition_snapshot tp_transition_snapshot[_NR_TP_TRANSITION_SYNC]; |
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static void tp_rcu_get_state(enum tp_transition_sync sync) |
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{ |
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struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync]; |
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|
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/* Keep the latest get_state snapshot. */ |
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snapshot->rcu = get_state_synchronize_rcu(); |
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snapshot->srcu = start_poll_synchronize_srcu(&tracepoint_srcu); |
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snapshot->ongoing = true; |
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} |
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static void tp_rcu_cond_sync(enum tp_transition_sync sync) |
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{ |
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struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync]; |
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if (!snapshot->ongoing) |
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return; |
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cond_synchronize_rcu(snapshot->rcu); |
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if (!poll_state_synchronize_srcu(&tracepoint_srcu, snapshot->srcu)) |
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synchronize_srcu(&tracepoint_srcu); |
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snapshot->ongoing = false; |
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} |
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/* Set to 1 to enable tracepoint debug output */ |
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static const int tracepoint_debug; |
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#ifdef CONFIG_MODULES |
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/* |
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* Tracepoint module list mutex protects the local module list. |
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*/ |
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static DEFINE_MUTEX(tracepoint_module_list_mutex); |
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|
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/* Local list of struct tp_module */ |
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static LIST_HEAD(tracepoint_module_list); |
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#endif /* CONFIG_MODULES */ |
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/* |
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* tracepoints_mutex protects the builtin and module tracepoints. |
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* tracepoints_mutex nests inside tracepoint_module_list_mutex. |
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*/ |
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static DEFINE_MUTEX(tracepoints_mutex); |
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static struct rcu_head *early_probes; |
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static bool ok_to_free_tracepoints; |
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/* |
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* Note about RCU : |
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* It is used to delay the free of multiple probes array until a quiescent |
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* state is reached. |
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*/ |
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struct tp_probes { |
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struct rcu_head rcu; |
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struct tracepoint_func probes[]; |
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}; |
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/* Called in removal of a func but failed to allocate a new tp_funcs */ |
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static void tp_stub_func(void) |
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{ |
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return; |
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} |
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static inline void *allocate_probes(int count) |
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{ |
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struct tp_probes *p = kmalloc(struct_size(p, probes, count), |
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GFP_KERNEL); |
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return p == NULL ? NULL : p->probes; |
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} |
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static void srcu_free_old_probes(struct rcu_head *head) |
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{ |
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kfree(container_of(head, struct tp_probes, rcu)); |
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} |
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static void rcu_free_old_probes(struct rcu_head *head) |
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{ |
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call_srcu(&tracepoint_srcu, head, srcu_free_old_probes); |
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} |
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static __init int release_early_probes(void) |
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{ |
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struct rcu_head *tmp; |
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ok_to_free_tracepoints = true; |
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while (early_probes) { |
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tmp = early_probes; |
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early_probes = tmp->next; |
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call_rcu(tmp, rcu_free_old_probes); |
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} |
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return 0; |
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} |
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/* SRCU is initialized at core_initcall */ |
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postcore_initcall(release_early_probes); |
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static inline void release_probes(struct tracepoint_func *old) |
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{ |
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if (old) { |
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struct tp_probes *tp_probes = container_of(old, |
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struct tp_probes, probes[0]); |
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/* |
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* We can't free probes if SRCU is not initialized yet. |
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* Postpone the freeing till after SRCU is initialized. |
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*/ |
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if (unlikely(!ok_to_free_tracepoints)) { |
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tp_probes->rcu.next = early_probes; |
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early_probes = &tp_probes->rcu; |
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return; |
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} |
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/* |
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* Tracepoint probes are protected by both sched RCU and SRCU, |
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* by calling the SRCU callback in the sched RCU callback we |
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* cover both cases. So let us chain the SRCU and sched RCU |
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* callbacks to wait for both grace periods. |
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*/ |
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call_rcu(&tp_probes->rcu, rcu_free_old_probes); |
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} |
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} |
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static void debug_print_probes(struct tracepoint_func *funcs) |
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{ |
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int i; |
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if (!tracepoint_debug || !funcs) |
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return; |
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for (i = 0; funcs[i].func; i++) |
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printk(KERN_DEBUG "Probe %d : %p\n", i, funcs[i].func); |
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} |
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static struct tracepoint_func * |
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func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func, |
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int prio) |
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{ |
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struct tracepoint_func *old, *new; |
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int iter_probes; /* Iterate over old probe array. */ |
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int nr_probes = 0; /* Counter for probes */ |
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int pos = -1; /* Insertion position into new array */ |
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if (WARN_ON(!tp_func->func)) |
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return ERR_PTR(-EINVAL); |
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debug_print_probes(*funcs); |
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old = *funcs; |
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if (old) { |
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/* (N -> N+1), (N != 0, 1) probes */ |
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for (iter_probes = 0; old[iter_probes].func; iter_probes++) { |
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if (old[iter_probes].func == tp_stub_func) |
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continue; /* Skip stub functions. */ |
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if (old[iter_probes].func == tp_func->func && |
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old[iter_probes].data == tp_func->data) |
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return ERR_PTR(-EEXIST); |
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nr_probes++; |
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} |
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} |
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/* + 2 : one for new probe, one for NULL func */ |
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new = allocate_probes(nr_probes + 2); |
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if (new == NULL) |
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return ERR_PTR(-ENOMEM); |
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if (old) { |
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nr_probes = 0; |
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for (iter_probes = 0; old[iter_probes].func; iter_probes++) { |
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if (old[iter_probes].func == tp_stub_func) |
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continue; |
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/* Insert before probes of lower priority */ |
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if (pos < 0 && old[iter_probes].prio < prio) |
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pos = nr_probes++; |
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new[nr_probes++] = old[iter_probes]; |
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} |
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if (pos < 0) |
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pos = nr_probes++; |
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/* nr_probes now points to the end of the new array */ |
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} else { |
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pos = 0; |
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nr_probes = 1; /* must point at end of array */ |
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} |
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new[pos] = *tp_func; |
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new[nr_probes].func = NULL; |
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*funcs = new; |
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debug_print_probes(*funcs); |
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return old; |
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} |
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static void *func_remove(struct tracepoint_func **funcs, |
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struct tracepoint_func *tp_func) |
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{ |
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int nr_probes = 0, nr_del = 0, i; |
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struct tracepoint_func *old, *new; |
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old = *funcs; |
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if (!old) |
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return ERR_PTR(-ENOENT); |
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debug_print_probes(*funcs); |
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/* (N -> M), (N > 1, M >= 0) probes */ |
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if (tp_func->func) { |
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for (nr_probes = 0; old[nr_probes].func; nr_probes++) { |
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if ((old[nr_probes].func == tp_func->func && |
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old[nr_probes].data == tp_func->data) || |
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old[nr_probes].func == tp_stub_func) |
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nr_del++; |
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} |
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} |
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/* |
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* If probe is NULL, then nr_probes = nr_del = 0, and then the |
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* entire entry will be removed. |
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*/ |
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if (nr_probes - nr_del == 0) { |
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/* N -> 0, (N > 1) */ |
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*funcs = NULL; |
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debug_print_probes(*funcs); |
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return old; |
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} else { |
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int j = 0; |
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/* N -> M, (N > 1, M > 0) */ |
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/* + 1 for NULL */ |
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new = allocate_probes(nr_probes - nr_del + 1); |
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if (new) { |
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for (i = 0; old[i].func; i++) { |
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if ((old[i].func != tp_func->func || |
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old[i].data != tp_func->data) && |
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old[i].func != tp_stub_func) |
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new[j++] = old[i]; |
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} |
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new[nr_probes - nr_del].func = NULL; |
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*funcs = new; |
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} else { |
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/* |
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* Failed to allocate, replace the old function |
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* with calls to tp_stub_func. |
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*/ |
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for (i = 0; old[i].func; i++) { |
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if (old[i].func == tp_func->func && |
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old[i].data == tp_func->data) |
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WRITE_ONCE(old[i].func, tp_stub_func); |
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} |
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*funcs = old; |
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} |
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} |
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debug_print_probes(*funcs); |
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return old; |
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} |
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/* |
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* Count the number of functions (enum tp_func_state) in a tp_funcs array. |
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*/ |
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static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs) |
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{ |
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if (!tp_funcs) |
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return TP_FUNC_0; |
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if (!tp_funcs[1].func) |
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return TP_FUNC_1; |
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if (!tp_funcs[2].func) |
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return TP_FUNC_2; |
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return TP_FUNC_N; /* 3 or more */ |
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} |
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static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs) |
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{ |
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void *func = tp->iterator; |
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/* Synthetic events do not have static call sites */ |
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if (!tp->static_call_key) |
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return; |
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if (nr_func_state(tp_funcs) == TP_FUNC_1) |
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func = tp_funcs[0].func; |
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__static_call_update(tp->static_call_key, tp->static_call_tramp, func); |
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} |
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/* |
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* Add the probe function to a tracepoint. |
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*/ |
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static int tracepoint_add_func(struct tracepoint *tp, |
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struct tracepoint_func *func, int prio, |
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bool warn) |
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{ |
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struct tracepoint_func *old, *tp_funcs; |
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int ret; |
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if (tp->regfunc && !static_key_enabled(&tp->key)) { |
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ret = tp->regfunc(); |
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if (ret < 0) |
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return ret; |
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} |
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tp_funcs = rcu_dereference_protected(tp->funcs, |
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lockdep_is_held(&tracepoints_mutex)); |
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old = func_add(&tp_funcs, func, prio); |
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if (IS_ERR(old)) { |
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WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM); |
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return PTR_ERR(old); |
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} |
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/* |
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* rcu_assign_pointer has as smp_store_release() which makes sure |
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* that the new probe callbacks array is consistent before setting |
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* a pointer to it. This array is referenced by __DO_TRACE from |
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* include/linux/tracepoint.h using rcu_dereference_sched(). |
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*/ |
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switch (nr_func_state(tp_funcs)) { |
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case TP_FUNC_1: /* 0->1 */ |
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/* |
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* Make sure new static func never uses old data after a |
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* 1->0->1 transition sequence. |
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*/ |
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tp_rcu_cond_sync(TP_TRANSITION_SYNC_1_0_1); |
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/* Set static call to first function */ |
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tracepoint_update_call(tp, tp_funcs); |
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/* Both iterator and static call handle NULL tp->funcs */ |
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rcu_assign_pointer(tp->funcs, tp_funcs); |
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static_key_enable(&tp->key); |
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break; |
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case TP_FUNC_2: /* 1->2 */ |
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/* Set iterator static call */ |
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tracepoint_update_call(tp, tp_funcs); |
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/* |
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* Iterator callback installed before updating tp->funcs. |
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* Requires ordering between RCU assign/dereference and |
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* static call update/call. |
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*/ |
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fallthrough; |
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case TP_FUNC_N: /* N->N+1 (N>1) */ |
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rcu_assign_pointer(tp->funcs, tp_funcs); |
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/* |
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* Make sure static func never uses incorrect data after a |
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* N->...->2->1 (N>1) transition sequence. |
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*/ |
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if (tp_funcs[0].data != old[0].data) |
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tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1); |
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break; |
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default: |
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WARN_ON_ONCE(1); |
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break; |
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} |
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release_probes(old); |
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return 0; |
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} |
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/* |
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* Remove a probe function from a tracepoint. |
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* Note: only waiting an RCU period after setting elem->call to the empty |
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* function insures that the original callback is not used anymore. This insured |
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* by preempt_disable around the call site. |
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*/ |
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static int tracepoint_remove_func(struct tracepoint *tp, |
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struct tracepoint_func *func) |
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{ |
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struct tracepoint_func *old, *tp_funcs; |
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tp_funcs = rcu_dereference_protected(tp->funcs, |
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lockdep_is_held(&tracepoints_mutex)); |
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old = func_remove(&tp_funcs, func); |
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if (WARN_ON_ONCE(IS_ERR(old))) |
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return PTR_ERR(old); |
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if (tp_funcs == old) |
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/* Failed allocating new tp_funcs, replaced func with stub */ |
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return 0; |
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switch (nr_func_state(tp_funcs)) { |
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case TP_FUNC_0: /* 1->0 */ |
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/* Removed last function */ |
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if (tp->unregfunc && static_key_enabled(&tp->key)) |
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tp->unregfunc(); |
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static_key_disable(&tp->key); |
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/* Set iterator static call */ |
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tracepoint_update_call(tp, tp_funcs); |
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/* Both iterator and static call handle NULL tp->funcs */ |
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rcu_assign_pointer(tp->funcs, NULL); |
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/* |
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* Make sure new static func never uses old data after a |
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* 1->0->1 transition sequence. |
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*/ |
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tp_rcu_get_state(TP_TRANSITION_SYNC_1_0_1); |
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break; |
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case TP_FUNC_1: /* 2->1 */ |
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rcu_assign_pointer(tp->funcs, tp_funcs); |
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/* |
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* Make sure static func never uses incorrect data after a |
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* N->...->2->1 (N>2) transition sequence. If the first |
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* element's data has changed, then force the synchronization |
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* to prevent current readers that have loaded the old data |
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* from calling the new function. |
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*/ |
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if (tp_funcs[0].data != old[0].data) |
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tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1); |
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tp_rcu_cond_sync(TP_TRANSITION_SYNC_N_2_1); |
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/* Set static call to first function */ |
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tracepoint_update_call(tp, tp_funcs); |
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break; |
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case TP_FUNC_2: /* N->N-1 (N>2) */ |
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fallthrough; |
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case TP_FUNC_N: |
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rcu_assign_pointer(tp->funcs, tp_funcs); |
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/* |
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* Make sure static func never uses incorrect data after a |
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* N->...->2->1 (N>2) transition sequence. |
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*/ |
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if (tp_funcs[0].data != old[0].data) |
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tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1); |
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break; |
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default: |
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WARN_ON_ONCE(1); |
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break; |
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} |
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release_probes(old); |
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return 0; |
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} |
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|
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/** |
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* tracepoint_probe_register_prio_may_exist - Connect a probe to a tracepoint with priority |
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* @tp: tracepoint |
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* @probe: probe handler |
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* @data: tracepoint data |
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* @prio: priority of this function over other registered functions |
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* |
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* Same as tracepoint_probe_register_prio() except that it will not warn |
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* if the tracepoint is already registered. |
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*/ |
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int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe, |
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void *data, int prio) |
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{ |
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struct tracepoint_func tp_func; |
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int ret; |
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|
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mutex_lock(&tracepoints_mutex); |
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tp_func.func = probe; |
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tp_func.data = data; |
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tp_func.prio = prio; |
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ret = tracepoint_add_func(tp, &tp_func, prio, false); |
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mutex_unlock(&tracepoints_mutex); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist); |
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|
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/** |
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* tracepoint_probe_register_prio - Connect a probe to a tracepoint with priority |
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* @tp: tracepoint |
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* @probe: probe handler |
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* @data: tracepoint data |
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* @prio: priority of this function over other registered functions |
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* |
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* Returns 0 if ok, error value on error. |
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* Note: if @tp is within a module, the caller is responsible for |
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* unregistering the probe before the module is gone. This can be |
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* performed either with a tracepoint module going notifier, or from |
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* within module exit functions. |
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*/ |
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int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, |
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void *data, int prio) |
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{ |
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struct tracepoint_func tp_func; |
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int ret; |
|
|
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mutex_lock(&tracepoints_mutex); |
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tp_func.func = probe; |
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tp_func.data = data; |
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tp_func.prio = prio; |
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ret = tracepoint_add_func(tp, &tp_func, prio, true); |
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mutex_unlock(&tracepoints_mutex); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio); |
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|
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/** |
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* tracepoint_probe_register - Connect a probe to a tracepoint |
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* @tp: tracepoint |
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* @probe: probe handler |
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* @data: tracepoint data |
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* |
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* Returns 0 if ok, error value on error. |
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* Note: if @tp is within a module, the caller is responsible for |
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* unregistering the probe before the module is gone. This can be |
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* performed either with a tracepoint module going notifier, or from |
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* within module exit functions. |
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*/ |
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int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data) |
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{ |
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return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO); |
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} |
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EXPORT_SYMBOL_GPL(tracepoint_probe_register); |
|
|
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/** |
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* tracepoint_probe_unregister - Disconnect a probe from a tracepoint |
|
* @tp: tracepoint |
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* @probe: probe function pointer |
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* @data: tracepoint data |
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* |
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* Returns 0 if ok, error value on error. |
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*/ |
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int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data) |
|
{ |
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struct tracepoint_func tp_func; |
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int ret; |
|
|
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mutex_lock(&tracepoints_mutex); |
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tp_func.func = probe; |
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tp_func.data = data; |
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ret = tracepoint_remove_func(tp, &tp_func); |
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mutex_unlock(&tracepoints_mutex); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); |
|
|
|
static void for_each_tracepoint_range( |
|
tracepoint_ptr_t *begin, tracepoint_ptr_t *end, |
|
void (*fct)(struct tracepoint *tp, void *priv), |
|
void *priv) |
|
{ |
|
tracepoint_ptr_t *iter; |
|
|
|
if (!begin) |
|
return; |
|
for (iter = begin; iter < end; iter++) |
|
fct(tracepoint_ptr_deref(iter), priv); |
|
} |
|
|
|
#ifdef CONFIG_MODULES |
|
bool trace_module_has_bad_taint(struct module *mod) |
|
{ |
|
return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) | |
|
(1 << TAINT_UNSIGNED_MODULE)); |
|
} |
|
|
|
static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list); |
|
|
|
/** |
|
* register_tracepoint_module_notifier - register tracepoint coming/going notifier |
|
* @nb: notifier block |
|
* |
|
* Notifiers registered with this function are called on module |
|
* coming/going with the tracepoint_module_list_mutex held. |
|
* The notifier block callback should expect a "struct tp_module" data |
|
* pointer. |
|
*/ |
|
int register_tracepoint_module_notifier(struct notifier_block *nb) |
|
{ |
|
struct tp_module *tp_mod; |
|
int ret; |
|
|
|
mutex_lock(&tracepoint_module_list_mutex); |
|
ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb); |
|
if (ret) |
|
goto end; |
|
list_for_each_entry(tp_mod, &tracepoint_module_list, list) |
|
(void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod); |
|
end: |
|
mutex_unlock(&tracepoint_module_list_mutex); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier); |
|
|
|
/** |
|
* unregister_tracepoint_module_notifier - unregister tracepoint coming/going notifier |
|
* @nb: notifier block |
|
* |
|
* The notifier block callback should expect a "struct tp_module" data |
|
* pointer. |
|
*/ |
|
int unregister_tracepoint_module_notifier(struct notifier_block *nb) |
|
{ |
|
struct tp_module *tp_mod; |
|
int ret; |
|
|
|
mutex_lock(&tracepoint_module_list_mutex); |
|
ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb); |
|
if (ret) |
|
goto end; |
|
list_for_each_entry(tp_mod, &tracepoint_module_list, list) |
|
(void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod); |
|
end: |
|
mutex_unlock(&tracepoint_module_list_mutex); |
|
return ret; |
|
|
|
} |
|
EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier); |
|
|
|
/* |
|
* Ensure the tracer unregistered the module's probes before the module |
|
* teardown is performed. Prevents leaks of probe and data pointers. |
|
*/ |
|
static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv) |
|
{ |
|
WARN_ON_ONCE(tp->funcs); |
|
} |
|
|
|
static int tracepoint_module_coming(struct module *mod) |
|
{ |
|
struct tp_module *tp_mod; |
|
int ret = 0; |
|
|
|
if (!mod->num_tracepoints) |
|
return 0; |
|
|
|
/* |
|
* We skip modules that taint the kernel, especially those with different |
|
* module headers (for forced load), to make sure we don't cause a crash. |
|
* Staging, out-of-tree, and unsigned GPL modules are fine. |
|
*/ |
|
if (trace_module_has_bad_taint(mod)) |
|
return 0; |
|
mutex_lock(&tracepoint_module_list_mutex); |
|
tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL); |
|
if (!tp_mod) { |
|
ret = -ENOMEM; |
|
goto end; |
|
} |
|
tp_mod->mod = mod; |
|
list_add_tail(&tp_mod->list, &tracepoint_module_list); |
|
blocking_notifier_call_chain(&tracepoint_notify_list, |
|
MODULE_STATE_COMING, tp_mod); |
|
end: |
|
mutex_unlock(&tracepoint_module_list_mutex); |
|
return ret; |
|
} |
|
|
|
static void tracepoint_module_going(struct module *mod) |
|
{ |
|
struct tp_module *tp_mod; |
|
|
|
if (!mod->num_tracepoints) |
|
return; |
|
|
|
mutex_lock(&tracepoint_module_list_mutex); |
|
list_for_each_entry(tp_mod, &tracepoint_module_list, list) { |
|
if (tp_mod->mod == mod) { |
|
blocking_notifier_call_chain(&tracepoint_notify_list, |
|
MODULE_STATE_GOING, tp_mod); |
|
list_del(&tp_mod->list); |
|
kfree(tp_mod); |
|
/* |
|
* Called the going notifier before checking for |
|
* quiescence. |
|
*/ |
|
for_each_tracepoint_range(mod->tracepoints_ptrs, |
|
mod->tracepoints_ptrs + mod->num_tracepoints, |
|
tp_module_going_check_quiescent, NULL); |
|
break; |
|
} |
|
} |
|
/* |
|
* In the case of modules that were tainted at "coming", we'll simply |
|
* walk through the list without finding it. We cannot use the "tainted" |
|
* flag on "going", in case a module taints the kernel only after being |
|
* loaded. |
|
*/ |
|
mutex_unlock(&tracepoint_module_list_mutex); |
|
} |
|
|
|
static int tracepoint_module_notify(struct notifier_block *self, |
|
unsigned long val, void *data) |
|
{ |
|
struct module *mod = data; |
|
int ret = 0; |
|
|
|
switch (val) { |
|
case MODULE_STATE_COMING: |
|
ret = tracepoint_module_coming(mod); |
|
break; |
|
case MODULE_STATE_LIVE: |
|
break; |
|
case MODULE_STATE_GOING: |
|
tracepoint_module_going(mod); |
|
break; |
|
case MODULE_STATE_UNFORMED: |
|
break; |
|
} |
|
return notifier_from_errno(ret); |
|
} |
|
|
|
static struct notifier_block tracepoint_module_nb = { |
|
.notifier_call = tracepoint_module_notify, |
|
.priority = 0, |
|
}; |
|
|
|
static __init int init_tracepoints(void) |
|
{ |
|
int ret; |
|
|
|
ret = register_module_notifier(&tracepoint_module_nb); |
|
if (ret) |
|
pr_warn("Failed to register tracepoint module enter notifier\n"); |
|
|
|
return ret; |
|
} |
|
__initcall(init_tracepoints); |
|
#endif /* CONFIG_MODULES */ |
|
|
|
/** |
|
* for_each_kernel_tracepoint - iteration on all kernel tracepoints |
|
* @fct: callback |
|
* @priv: private data |
|
*/ |
|
void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv), |
|
void *priv) |
|
{ |
|
for_each_tracepoint_range(__start___tracepoints_ptrs, |
|
__stop___tracepoints_ptrs, fct, priv); |
|
} |
|
EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint); |
|
|
|
#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS |
|
|
|
/* NB: reg/unreg are called while guarded with the tracepoints_mutex */ |
|
static int sys_tracepoint_refcount; |
|
|
|
int syscall_regfunc(void) |
|
{ |
|
struct task_struct *p, *t; |
|
|
|
if (!sys_tracepoint_refcount) { |
|
read_lock(&tasklist_lock); |
|
for_each_process_thread(p, t) { |
|
set_task_syscall_work(t, SYSCALL_TRACEPOINT); |
|
} |
|
read_unlock(&tasklist_lock); |
|
} |
|
sys_tracepoint_refcount++; |
|
|
|
return 0; |
|
} |
|
|
|
void syscall_unregfunc(void) |
|
{ |
|
struct task_struct *p, *t; |
|
|
|
sys_tracepoint_refcount--; |
|
if (!sys_tracepoint_refcount) { |
|
read_lock(&tasklist_lock); |
|
for_each_process_thread(p, t) { |
|
clear_task_syscall_work(t, SYSCALL_TRACEPOINT); |
|
} |
|
read_unlock(&tasklist_lock); |
|
} |
|
} |
|
#endif
|
|
|