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| author | Vincent Donnefort <vdonnefort@google.com> | 2024-02-20 20:23:07 +0000 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-03-18 10:12:47 -0400 |
| commit | 180e4e390978af9d0cc060e87920c462276453b9 (patch) | |
| tree | ef13bfaaa3fd1823bc8fc0969866e951c0975e33 /kernel/trace/trace.h | |
| parent | b70f2938242a028f8e9473781ede175486a59dc8 (diff) | |
| download | lwn-180e4e390978af9d0cc060e87920c462276453b9.tar.gz lwn-180e4e390978af9d0cc060e87920c462276453b9.zip | |
tracing: Add snapshot refcount
When a ring-buffer is memory mapped by user-space, no trace or
ring-buffer swap is possible. This means the snapshot feature is
mutually exclusive with the memory mapping. Having a refcount on
snapshot users will help to know if a mapping is possible or not.
Instead of relying on the global trace_types_lock, a new spinlock is
introduced to serialize accesses to trace_array->snapshot. This intends
to allow access to that variable in a context where the mmap lock is
already held.
Link: https://lore.kernel.org/linux-trace-kernel/20240220202310.2489614-4-vdonnefort@google.com
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace.h')
| -rw-r--r-- | kernel/trace/trace.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index e4f0714d7a49..64450615ca0c 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -334,8 +334,8 @@ struct trace_array { */ struct array_buffer max_buffer; bool allocated_snapshot; -#endif -#ifdef CONFIG_TRACER_MAX_TRACE + spinlock_t snapshot_trigger_lock; + unsigned int snapshot; unsigned long max_latency; #ifdef CONFIG_FSNOTIFY struct dentry *d_max_latency; @@ -1983,12 +1983,16 @@ static inline void trace_event_eval_update(struct trace_eval_map **map, int len) #ifdef CONFIG_TRACER_SNAPSHOT void tracing_snapshot_instance(struct trace_array *tr); int tracing_alloc_snapshot_instance(struct trace_array *tr); +int tracing_arm_snapshot(struct trace_array *tr); +void tracing_disarm_snapshot(struct trace_array *tr); #else static inline void tracing_snapshot_instance(struct trace_array *tr) { } static inline int tracing_alloc_snapshot_instance(struct trace_array *tr) { return 0; } +static inline int tracing_arm_snapshot(struct trace_array *tr) { return 0; } +static inline void tracing_disarm_snapshot(struct trace_array *tr) { } #endif #ifdef CONFIG_PREEMPT_TRACER |