diff options
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 192 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 56 | ||||
| -rw-r--r-- | kernel/trace/trace_sched_wakeup.c | 2 |
3 files changed, 244 insertions, 6 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b477926ac3bc..9f4d56f74b46 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -894,7 +894,7 @@ int __trace_bputs(unsigned long ip, const char *str) EXPORT_SYMBOL_GPL(__trace_bputs); #ifdef CONFIG_TRACER_SNAPSHOT -void tracing_snapshot_instance(struct trace_array *tr) +void tracing_snapshot_instance_cond(struct trace_array *tr, void *cond_data) { struct tracer *tracer = tr->current_trace; unsigned long flags; @@ -920,10 +920,15 @@ void tracing_snapshot_instance(struct trace_array *tr) } local_irq_save(flags); - update_max_tr(tr, current, smp_processor_id()); + update_max_tr(tr, current, smp_processor_id(), cond_data); local_irq_restore(flags); } +void tracing_snapshot_instance(struct trace_array *tr) +{ + tracing_snapshot_instance_cond(tr, NULL); +} + /** * tracing_snapshot - take a snapshot of the current buffer. * @@ -946,6 +951,54 @@ void tracing_snapshot(void) } EXPORT_SYMBOL_GPL(tracing_snapshot); +/** + * tracing_snapshot_cond - conditionally take a snapshot of the current buffer. + * @tr: The tracing instance to snapshot + * @cond_data: The data to be tested conditionally, and possibly saved + * + * This is the same as tracing_snapshot() except that the snapshot is + * conditional - the snapshot will only happen if the + * cond_snapshot.update() implementation receiving the cond_data + * returns true, which means that the trace array's cond_snapshot + * update() operation used the cond_data to determine whether the + * snapshot should be taken, and if it was, presumably saved it along + * with the snapshot. + */ +void tracing_snapshot_cond(struct trace_array *tr, void *cond_data) +{ + tracing_snapshot_instance_cond(tr, cond_data); +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond); + +/** + * tracing_snapshot_cond_data - get the user data associated with a snapshot + * @tr: The tracing instance + * + * When the user enables a conditional snapshot using + * tracing_snapshot_cond_enable(), the user-defined cond_data is saved + * with the snapshot. This accessor is used to retrieve it. + * + * Should not be called from cond_snapshot.update(), since it takes + * the tr->max_lock lock, which the code calling + * cond_snapshot.update() has already done. + * + * Returns the cond_data associated with the trace array's snapshot. + */ +void *tracing_cond_snapshot_data(struct trace_array *tr) +{ + void *cond_data = NULL; + + arch_spin_lock(&tr->max_lock); + + if (tr->cond_snapshot) + cond_data = tr->cond_snapshot->cond_data; + + arch_spin_unlock(&tr->max_lock); + + return cond_data; +} +EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data); + static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf, struct trace_buffer *size_buf, int cpu_id); static void set_buffer_entries(struct trace_buffer *buf, unsigned long val); @@ -1025,12 +1078,103 @@ void tracing_snapshot_alloc(void) tracing_snapshot(); } EXPORT_SYMBOL_GPL(tracing_snapshot_alloc); + +/** + * tracing_snapshot_cond_enable - enable conditional snapshot for an instance + * @tr: The tracing instance + * @cond_data: User data to associate with the snapshot + * @update: Implementation of the cond_snapshot update function + * + * Check whether the conditional snapshot for the given instance has + * already been enabled, or if the current tracer is already using a + * snapshot; if so, return -EBUSY, else create a cond_snapshot and + * save the cond_data and update function inside. + * + * Returns 0 if successful, error otherwise. + */ +int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, + cond_update_fn_t update) +{ + struct cond_snapshot *cond_snapshot; + int ret = 0; + + cond_snapshot = kzalloc(sizeof(*cond_snapshot), GFP_KERNEL); + if (!cond_snapshot) + return -ENOMEM; + + cond_snapshot->cond_data = cond_data; + cond_snapshot->update = update; + + mutex_lock(&trace_types_lock); + + ret = tracing_alloc_snapshot_instance(tr); + if (ret) + goto fail_unlock; + + if (tr->current_trace->use_max_tr) { + ret = -EBUSY; + goto fail_unlock; + } + + if (tr->cond_snapshot) { + ret = -EBUSY; + goto fail_unlock; + } + + arch_spin_lock(&tr->max_lock); + tr->cond_snapshot = cond_snapshot; + arch_spin_unlock(&tr->max_lock); + + mutex_unlock(&trace_types_lock); + + return ret; + + fail_unlock: + mutex_unlock(&trace_types_lock); + kfree(cond_snapshot); + return ret; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable); + +/** + * tracing_snapshot_cond_disable - disable conditional snapshot for an instance + * @tr: The tracing instance + * + * Check whether the conditional snapshot for the given instance is + * enabled; if so, free the cond_snapshot associated with it, + * otherwise return -EINVAL. + * + * Returns 0 if successful, error otherwise. + */ +int tracing_snapshot_cond_disable(struct trace_array *tr) +{ + int ret = 0; + + arch_spin_lock(&tr->max_lock); + + if (!tr->cond_snapshot) + ret = -EINVAL; + else { + kfree(tr->cond_snapshot); + tr->cond_snapshot = NULL; + } + + arch_spin_unlock(&tr->max_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable); #else void tracing_snapshot(void) { WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used"); } EXPORT_SYMBOL_GPL(tracing_snapshot); +void tracing_snapshot_cond(struct trace_array *tr, void *cond_data) +{ + WARN_ONCE(1, "Snapshot feature not enabled, but internal conditional snapshot used"); +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond); int tracing_alloc_snapshot(void) { WARN_ONCE(1, "Snapshot feature not enabled, but snapshot allocation used"); @@ -1043,6 +1187,21 @@ void tracing_snapshot_alloc(void) tracing_snapshot(); } EXPORT_SYMBOL_GPL(tracing_snapshot_alloc); +void *tracing_cond_snapshot_data(struct trace_array *tr) +{ + return NULL; +} +EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data); +int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update) +{ + return -ENODEV; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable); +int tracing_snapshot_cond_disable(struct trace_array *tr) +{ + return false; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable); #endif /* CONFIG_TRACER_SNAPSHOT */ void tracer_tracing_off(struct trace_array *tr) @@ -1354,12 +1513,14 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) * @tr: tracer * @tsk: the task with the latency * @cpu: The cpu that initiated the trace. + * @cond_data: User data associated with a conditional snapshot * * Flip the buffers between the @tr and the max_tr and record information * about which task was the cause of this latency. */ void -update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) +update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu, + void *cond_data) { if (tr->stop_count) return; @@ -1380,9 +1541,15 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) else ring_buffer_record_off(tr->max_buffer.buffer); +#ifdef CONFIG_TRACER_SNAPSHOT + if (tr->cond_snapshot && !tr->cond_snapshot->update(tr, cond_data)) + goto out_unlock; +#endif swap(tr->trace_buffer.buffer, tr->max_buffer.buffer); __update_max_tr(tr, tsk, cpu); + + out_unlock: arch_spin_unlock(&tr->max_lock); } @@ -5396,6 +5563,16 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf) if (t == tr->current_trace) goto out; +#ifdef CONFIG_TRACER_SNAPSHOT + if (t->use_max_tr) { + arch_spin_lock(&tr->max_lock); + if (tr->cond_snapshot) + ret = -EBUSY; + arch_spin_unlock(&tr->max_lock); + if (ret) + goto out; + } +#endif /* Some tracers won't work on kernel command line */ if (system_state < SYSTEM_RUNNING && t->noboot) { pr_warn("Tracer '%s' is not allowed on command line, ignored\n", @@ -6477,6 +6654,13 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, goto out; } + arch_spin_lock(&tr->max_lock); + if (tr->cond_snapshot) + ret = -EBUSY; + arch_spin_unlock(&tr->max_lock); + if (ret) + goto out; + switch (val) { case 0: if (iter->cpu_file != RING_BUFFER_ALL_CPUS) { @@ -6502,7 +6686,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, local_irq_disable(); /* Now, we're going to swap */ if (iter->cpu_file == RING_BUFFER_ALL_CPUS) - update_max_tr(tr, current, smp_processor_id()); + update_max_tr(tr, current, smp_processor_id(), NULL); else update_max_tr_single(tr, current, iter->cpu_file); local_irq_enable(); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index ae7df090b93e..d80cee49e0eb 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -194,6 +194,51 @@ struct trace_pid_list { unsigned long *pids; }; +typedef bool (*cond_update_fn_t)(struct trace_array *tr, void *cond_data); + +/** + * struct cond_snapshot - conditional snapshot data and callback + * + * The cond_snapshot structure encapsulates a callback function and + * data associated with the snapshot for a given tracing instance. + * + * When a snapshot is taken conditionally, by invoking + * tracing_snapshot_cond(tr, cond_data), the cond_data passed in is + * passed in turn to the cond_snapshot.update() function. That data + * can be compared by the update() implementation with the cond_data + * contained wihin the struct cond_snapshot instance associated with + * the trace_array. Because the tr->max_lock is held throughout the + * update() call, the update() function can directly retrieve the + * cond_snapshot and cond_data associated with the per-instance + * snapshot associated with the trace_array. + * + * The cond_snapshot.update() implementation can save data to be + * associated with the snapshot if it decides to, and returns 'true' + * in that case, or it returns 'false' if the conditional snapshot + * shouldn't be taken. + * + * The cond_snapshot instance is created and associated with the + * user-defined cond_data by tracing_cond_snapshot_enable(). + * Likewise, the cond_snapshot instance is destroyed and is no longer + * associated with the trace instance by + * tracing_cond_snapshot_disable(). + * + * The method below is required. + * + * @update: When a conditional snapshot is invoked, the update() + * callback function is invoked with the tr->max_lock held. The + * update() implementation signals whether or not to actually + * take the snapshot, by returning 'true' if so, 'false' if no + * snapshot should be taken. Because the max_lock is held for + * the duration of update(), the implementation is safe to + * directly retrieven and save any implementation data it needs + * to in association with the snapshot. + */ +struct cond_snapshot { + void *cond_data; + cond_update_fn_t update; +}; + /* * The trace array - an array of per-CPU trace arrays. This is the * highest level data structure that individual tracers deal with. @@ -277,6 +322,9 @@ struct trace_array { #endif int time_stamp_abs_ref; struct list_head hist_vars; +#ifdef CONFIG_TRACER_SNAPSHOT + struct cond_snapshot *cond_snapshot; +#endif }; enum { @@ -727,7 +775,8 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, const char __user *ubuf, size_t cnt); #ifdef CONFIG_TRACER_MAX_TRACE -void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu); +void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu, + void *cond_data); void update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu); #endif /* CONFIG_TRACER_MAX_TRACE */ @@ -1810,6 +1859,11 @@ static inline bool event_command_needs_rec(struct event_command *cmd_ops) extern int trace_event_enable_disable(struct trace_event_file *file, int enable, int soft_disable); extern int tracing_alloc_snapshot(void); +extern void tracing_snapshot_cond(struct trace_array *tr, void *cond_data); +extern int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update); + +extern int tracing_snapshot_cond_disable(struct trace_array *tr); +extern void *tracing_cond_snapshot_data(struct trace_array *tr); extern const char *__start___trace_bprintk_fmt[]; extern const char *__stop___trace_bprintk_fmt[]; diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index f4fe7d1781e9..743b2b520d34 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -486,7 +486,7 @@ probe_wakeup_sched_switch(void *ignore, bool preempt, if (likely(!is_tracing_stopped())) { wakeup_trace->max_latency = delta; - update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu); + update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu, NULL); } out_unlock: |