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465 lines
11 KiB
465 lines
11 KiB
/** |
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* @file cpu_buffer.c |
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* |
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* @remark Copyright 2002-2009 OProfile authors |
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* @remark Read the file COPYING |
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* |
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* @author John Levon <[email protected]> |
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* @author Barry Kasindorf <[email protected]> |
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* @author Robert Richter <[email protected]> |
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* |
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* Each CPU has a local buffer that stores PC value/event |
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* pairs. We also log context switches when we notice them. |
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* Eventually each CPU's buffer is processed into the global |
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* event buffer by sync_buffer(). |
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* |
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* We use a local buffer for two reasons: an NMI or similar |
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* interrupt cannot synchronise, and high sampling rates |
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* would lead to catastrophic global synchronisation if |
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* a global buffer was used. |
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*/ |
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#include <linux/sched.h> |
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#include <linux/oprofile.h> |
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#include <linux/errno.h> |
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#include <asm/ptrace.h> |
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#include "event_buffer.h" |
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#include "cpu_buffer.h" |
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#include "buffer_sync.h" |
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#include "oprof.h" |
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#define OP_BUFFER_FLAGS 0 |
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static struct trace_buffer *op_ring_buffer; |
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DEFINE_PER_CPU(struct oprofile_cpu_buffer, op_cpu_buffer); |
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static void wq_sync_buffer(struct work_struct *work); |
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#define DEFAULT_TIMER_EXPIRE (HZ / 10) |
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static int work_enabled; |
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unsigned long oprofile_get_cpu_buffer_size(void) |
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{ |
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return oprofile_cpu_buffer_size; |
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} |
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void oprofile_cpu_buffer_inc_smpl_lost(void) |
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{ |
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struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer); |
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cpu_buf->sample_lost_overflow++; |
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} |
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void free_cpu_buffers(void) |
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{ |
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if (op_ring_buffer) |
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ring_buffer_free(op_ring_buffer); |
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op_ring_buffer = NULL; |
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} |
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#define RB_EVENT_HDR_SIZE 4 |
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int alloc_cpu_buffers(void) |
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{ |
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int i; |
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unsigned long buffer_size = oprofile_cpu_buffer_size; |
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unsigned long byte_size = buffer_size * (sizeof(struct op_sample) + |
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RB_EVENT_HDR_SIZE); |
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op_ring_buffer = ring_buffer_alloc(byte_size, OP_BUFFER_FLAGS); |
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if (!op_ring_buffer) |
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goto fail; |
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for_each_possible_cpu(i) { |
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struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i); |
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b->last_task = NULL; |
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b->last_is_kernel = -1; |
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b->tracing = 0; |
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b->buffer_size = buffer_size; |
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b->sample_received = 0; |
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b->sample_lost_overflow = 0; |
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b->backtrace_aborted = 0; |
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b->sample_invalid_eip = 0; |
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b->cpu = i; |
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INIT_DELAYED_WORK(&b->work, wq_sync_buffer); |
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} |
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return 0; |
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fail: |
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free_cpu_buffers(); |
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return -ENOMEM; |
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} |
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void start_cpu_work(void) |
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{ |
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int i; |
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work_enabled = 1; |
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for_each_online_cpu(i) { |
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struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i); |
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/* |
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* Spread the work by 1 jiffy per cpu so they dont all |
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* fire at once. |
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*/ |
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schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i); |
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} |
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} |
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void end_cpu_work(void) |
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{ |
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work_enabled = 0; |
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} |
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void flush_cpu_work(void) |
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{ |
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int i; |
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for_each_online_cpu(i) { |
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struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i); |
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/* these works are per-cpu, no need for flush_sync */ |
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flush_delayed_work(&b->work); |
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} |
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} |
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/* |
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* This function prepares the cpu buffer to write a sample. |
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* |
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* Struct op_entry is used during operations on the ring buffer while |
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* struct op_sample contains the data that is stored in the ring |
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* buffer. Struct entry can be uninitialized. The function reserves a |
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* data array that is specified by size. Use |
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* op_cpu_buffer_write_commit() after preparing the sample. In case of |
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* errors a null pointer is returned, otherwise the pointer to the |
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* sample. |
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* |
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*/ |
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struct op_sample |
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*op_cpu_buffer_write_reserve(struct op_entry *entry, unsigned long size) |
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{ |
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entry->event = ring_buffer_lock_reserve |
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(op_ring_buffer, sizeof(struct op_sample) + |
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size * sizeof(entry->sample->data[0])); |
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if (!entry->event) |
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return NULL; |
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entry->sample = ring_buffer_event_data(entry->event); |
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entry->size = size; |
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entry->data = entry->sample->data; |
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return entry->sample; |
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} |
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int op_cpu_buffer_write_commit(struct op_entry *entry) |
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{ |
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return ring_buffer_unlock_commit(op_ring_buffer, entry->event); |
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} |
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struct op_sample *op_cpu_buffer_read_entry(struct op_entry *entry, int cpu) |
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{ |
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struct ring_buffer_event *e; |
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e = ring_buffer_consume(op_ring_buffer, cpu, NULL, NULL); |
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if (!e) |
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return NULL; |
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entry->event = e; |
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entry->sample = ring_buffer_event_data(e); |
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entry->size = (ring_buffer_event_length(e) - sizeof(struct op_sample)) |
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/ sizeof(entry->sample->data[0]); |
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entry->data = entry->sample->data; |
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return entry->sample; |
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} |
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unsigned long op_cpu_buffer_entries(int cpu) |
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{ |
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return ring_buffer_entries_cpu(op_ring_buffer, cpu); |
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} |
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static int |
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op_add_code(struct oprofile_cpu_buffer *cpu_buf, unsigned long backtrace, |
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int is_kernel, struct task_struct *task) |
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{ |
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struct op_entry entry; |
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struct op_sample *sample; |
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unsigned long flags; |
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int size; |
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flags = 0; |
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if (backtrace) |
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flags |= TRACE_BEGIN; |
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/* notice a switch from user->kernel or vice versa */ |
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is_kernel = !!is_kernel; |
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if (cpu_buf->last_is_kernel != is_kernel) { |
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cpu_buf->last_is_kernel = is_kernel; |
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flags |= KERNEL_CTX_SWITCH; |
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if (is_kernel) |
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flags |= IS_KERNEL; |
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} |
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/* notice a task switch */ |
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if (cpu_buf->last_task != task) { |
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cpu_buf->last_task = task; |
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flags |= USER_CTX_SWITCH; |
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} |
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if (!flags) |
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/* nothing to do */ |
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return 0; |
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if (flags & USER_CTX_SWITCH) |
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size = 1; |
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else |
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size = 0; |
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sample = op_cpu_buffer_write_reserve(&entry, size); |
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if (!sample) |
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return -ENOMEM; |
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sample->eip = ESCAPE_CODE; |
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sample->event = flags; |
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if (size) |
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op_cpu_buffer_add_data(&entry, (unsigned long)task); |
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op_cpu_buffer_write_commit(&entry); |
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return 0; |
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} |
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static inline int |
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op_add_sample(struct oprofile_cpu_buffer *cpu_buf, |
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unsigned long pc, unsigned long event) |
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{ |
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struct op_entry entry; |
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struct op_sample *sample; |
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sample = op_cpu_buffer_write_reserve(&entry, 0); |
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if (!sample) |
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return -ENOMEM; |
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sample->eip = pc; |
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sample->event = event; |
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return op_cpu_buffer_write_commit(&entry); |
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} |
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/* |
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* This must be safe from any context. |
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* |
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* is_kernel is needed because on some architectures you cannot |
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* tell if you are in kernel or user space simply by looking at |
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* pc. We tag this in the buffer by generating kernel enter/exit |
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* events whenever is_kernel changes |
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*/ |
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static int |
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log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc, |
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unsigned long backtrace, int is_kernel, unsigned long event, |
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struct task_struct *task) |
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{ |
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struct task_struct *tsk = task ? task : current; |
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cpu_buf->sample_received++; |
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if (pc == ESCAPE_CODE) { |
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cpu_buf->sample_invalid_eip++; |
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return 0; |
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} |
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if (op_add_code(cpu_buf, backtrace, is_kernel, tsk)) |
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goto fail; |
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if (op_add_sample(cpu_buf, pc, event)) |
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goto fail; |
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return 1; |
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fail: |
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cpu_buf->sample_lost_overflow++; |
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return 0; |
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} |
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static inline void oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf) |
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{ |
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cpu_buf->tracing = 1; |
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} |
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static inline void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf) |
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{ |
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cpu_buf->tracing = 0; |
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} |
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static inline void |
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__oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs, |
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unsigned long event, int is_kernel, |
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struct task_struct *task) |
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{ |
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struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer); |
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unsigned long backtrace = oprofile_backtrace_depth; |
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/* |
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* if log_sample() fail we can't backtrace since we lost the |
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* source of this event |
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*/ |
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if (!log_sample(cpu_buf, pc, backtrace, is_kernel, event, task)) |
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/* failed */ |
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return; |
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if (!backtrace) |
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return; |
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oprofile_begin_trace(cpu_buf); |
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oprofile_ops.backtrace(regs, backtrace); |
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oprofile_end_trace(cpu_buf); |
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} |
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void oprofile_add_ext_hw_sample(unsigned long pc, struct pt_regs * const regs, |
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unsigned long event, int is_kernel, |
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struct task_struct *task) |
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{ |
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__oprofile_add_ext_sample(pc, regs, event, is_kernel, task); |
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} |
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void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs, |
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unsigned long event, int is_kernel) |
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{ |
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__oprofile_add_ext_sample(pc, regs, event, is_kernel, NULL); |
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} |
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void oprofile_add_sample(struct pt_regs * const regs, unsigned long event) |
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{ |
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int is_kernel; |
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unsigned long pc; |
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if (likely(regs)) { |
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is_kernel = !user_mode(regs); |
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pc = profile_pc(regs); |
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} else { |
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is_kernel = 0; /* This value will not be used */ |
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pc = ESCAPE_CODE; /* as this causes an early return. */ |
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} |
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__oprofile_add_ext_sample(pc, regs, event, is_kernel, NULL); |
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} |
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/* |
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* Add samples with data to the ring buffer. |
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* |
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* Use oprofile_add_data(&entry, val) to add data and |
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* oprofile_write_commit(&entry) to commit the sample. |
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*/ |
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void |
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oprofile_write_reserve(struct op_entry *entry, struct pt_regs * const regs, |
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unsigned long pc, int code, int size) |
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{ |
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struct op_sample *sample; |
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int is_kernel = !user_mode(regs); |
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struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer); |
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cpu_buf->sample_received++; |
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/* no backtraces for samples with data */ |
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if (op_add_code(cpu_buf, 0, is_kernel, current)) |
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goto fail; |
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sample = op_cpu_buffer_write_reserve(entry, size + 2); |
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if (!sample) |
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goto fail; |
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sample->eip = ESCAPE_CODE; |
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sample->event = 0; /* no flags */ |
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op_cpu_buffer_add_data(entry, code); |
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op_cpu_buffer_add_data(entry, pc); |
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return; |
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fail: |
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entry->event = NULL; |
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cpu_buf->sample_lost_overflow++; |
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} |
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int oprofile_add_data(struct op_entry *entry, unsigned long val) |
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{ |
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if (!entry->event) |
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return 0; |
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return op_cpu_buffer_add_data(entry, val); |
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} |
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int oprofile_add_data64(struct op_entry *entry, u64 val) |
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{ |
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if (!entry->event) |
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return 0; |
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if (op_cpu_buffer_get_size(entry) < 2) |
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/* |
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* the function returns 0 to indicate a too small |
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* buffer, even if there is some space left |
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*/ |
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return 0; |
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if (!op_cpu_buffer_add_data(entry, (u32)val)) |
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return 0; |
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return op_cpu_buffer_add_data(entry, (u32)(val >> 32)); |
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} |
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int oprofile_write_commit(struct op_entry *entry) |
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{ |
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if (!entry->event) |
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return -EINVAL; |
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return op_cpu_buffer_write_commit(entry); |
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} |
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void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event) |
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{ |
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struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer); |
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log_sample(cpu_buf, pc, 0, is_kernel, event, NULL); |
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} |
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void oprofile_add_trace(unsigned long pc) |
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{ |
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struct oprofile_cpu_buffer *cpu_buf = this_cpu_ptr(&op_cpu_buffer); |
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if (!cpu_buf->tracing) |
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return; |
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/* |
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* broken frame can give an eip with the same value as an |
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* escape code, abort the trace if we get it |
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*/ |
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if (pc == ESCAPE_CODE) |
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goto fail; |
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if (op_add_sample(cpu_buf, pc, 0)) |
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goto fail; |
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return; |
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fail: |
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cpu_buf->tracing = 0; |
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cpu_buf->backtrace_aborted++; |
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return; |
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} |
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/* |
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* This serves to avoid cpu buffer overflow, and makes sure |
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* the task mortuary progresses |
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* |
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* By using schedule_delayed_work_on and then schedule_delayed_work |
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* we guarantee this will stay on the correct cpu |
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*/ |
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static void wq_sync_buffer(struct work_struct *work) |
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{ |
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struct oprofile_cpu_buffer *b = |
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container_of(work, struct oprofile_cpu_buffer, work.work); |
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if (b->cpu != smp_processor_id() && !cpu_online(b->cpu)) { |
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cancel_delayed_work(&b->work); |
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return; |
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} |
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sync_buffer(b->cpu); |
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/* don't re-add the work if we're shutting down */ |
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if (work_enabled) |
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schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE); |
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}
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