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lttng-ust(3): document liblttng-ust-fd
[lttng-ust.git]
/
libringbuffer
/
frontend_api.h
diff --git
a/libringbuffer/frontend_api.h
b/libringbuffer/frontend_api.h
index 6a06bba2c2393ba139bc506a8f88bb4027b59ea9..140159739feebc954f68d39b33806e3778f4ca01 100644
(file)
--- a/
libringbuffer/frontend_api.h
+++ b/
libringbuffer/frontend_api.h
@@
-37,10
+37,10
@@
/**
* lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit.
*
/**
* lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit.
*
- *
Grabs RCU read-side lock and keeps a ring buffer nesting count as
- *
supplementary safety net to ensure tracer client code will never
- *
trigger an endless recursion. Returns the processor ID on success,
- *
-EPERM on failure (nesting count
too high).
+ *
Keeps a ring buffer nesting count as supplementary safety net to
+ *
ensure tracer client code will never trigger an endless recursion.
+ *
Returns the processor ID on success, -EPERM on failure (nesting count
+ * too high).
*
* asm volatile and "memory" clobber prevent the compiler from moving
* instructions out of the ring buffer nesting count. This is required to ensure
*
* asm volatile and "memory" clobber prevent the compiler from moving
* instructions out of the ring buffer nesting count. This is required to ensure
@@
-53,15
+53,13
@@
int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *confi
{
int cpu, nesting;
{
int cpu, nesting;
- rcu_read_lock();
cpu = lttng_ust_get_cpu();
cpu = lttng_ust_get_cpu();
- nesting = ++
lib_ring_buffer_nesting; /* TLS */
+ nesting = ++
URCU_TLS(lib_ring_buffer_nesting);
cmm_barrier();
if (caa_unlikely(nesting > 4)) {
WARN_ON_ONCE(1);
cmm_barrier();
if (caa_unlikely(nesting > 4)) {
WARN_ON_ONCE(1);
- lib_ring_buffer_nesting--; /* TLS */
- rcu_read_unlock();
+ URCU_TLS(lib_ring_buffer_nesting)--;
return -EPERM;
} else
return cpu;
return -EPERM;
} else
return cpu;
@@
-74,8
+72,7
@@
static inline
void lib_ring_buffer_put_cpu(const struct lttng_ust_lib_ring_buffer_config *config)
{
cmm_barrier();
void lib_ring_buffer_put_cpu(const struct lttng_ust_lib_ring_buffer_config *config)
{
cmm_barrier();
- lib_ring_buffer_nesting--; /* TLS */
- rcu_read_unlock();
+ URCU_TLS(lib_ring_buffer_nesting)--; /* TLS */
}
/*
}
/*
@@
-163,14
+160,16
@@
int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi
unsigned long o_begin, o_end, o_old;
size_t before_hdr_pad = 0;
unsigned long o_begin, o_end, o_old;
size_t before_hdr_pad = 0;
- if (
uatomic_read(&chan->record_disabled
))
+ if (
caa_unlikely(uatomic_read(&chan->record_disabled)
))
return -EAGAIN;
if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp);
else
buf = shmp(handle, chan->backend.buf[0].shmp);
return -EAGAIN;
if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp);
else
buf = shmp(handle, chan->backend.buf[0].shmp);
- if (uatomic_read(&buf->record_disabled))
+ if (caa_unlikely(!buf))
+ return -EIO;
+ if (caa_unlikely(uatomic_read(&buf->record_disabled)))
return -EAGAIN;
ctx->buf = buf;
return -EAGAIN;
ctx->buf = buf;
@@
-253,11
+252,16
@@
void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *confi
unsigned long offset_end = ctx->buf_offset;
unsigned long endidx = subbuf_index(offset_end - 1, chan);
unsigned long commit_count;
unsigned long offset_end = ctx->buf_offset;
unsigned long endidx = subbuf_index(offset_end - 1, chan);
unsigned long commit_count;
+ struct commit_counters_hot *cc_hot = shmp_index(handle,
+ buf->commit_hot, endidx);
+
+ if (caa_unlikely(!cc_hot))
+ return;
/*
* Must count record before incrementing the commit count.
*/
/*
* Must count record before incrementing the commit count.
*/
- subbuffer_count_record(config, &buf->backend, endidx, handle);
+ subbuffer_count_record(config,
ctx,
&buf->backend, endidx, handle);
/*
* Order all writes to buffer before the commit count update that will
/*
* Order all writes to buffer before the commit count update that will
@@
-265,7
+269,7
@@
void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *confi
*/
cmm_smp_wmb();
*/
cmm_smp_wmb();
- v_add(config, ctx->slot_size, &
shmp_index(handle, buf->commit_hot, endidx)
->cc);
+ v_add(config, ctx->slot_size, &
cc_hot
->cc);
/*
* commit count read can race with concurrent OOO commit count updates.
/*
* commit count read can race with concurrent OOO commit count updates.
@@
-285,17
+289,16
@@
void lib_ring_buffer_commit(const struct lttng_ust_lib_ring_buffer_config *confi
* count reaches back the reserve offset for a specific sub-buffer,
* which is completely independent of the order.
*/
* count reaches back the reserve offset for a specific sub-buffer,
* which is completely independent of the order.
*/
- commit_count = v_read(config, &
shmp_index(handle, buf->commit_hot, endidx)
->cc);
+ commit_count = v_read(config, &
cc_hot
->cc);
lib_ring_buffer_check_deliver(config, buf, chan, offset_end - 1,
lib_ring_buffer_check_deliver(config, buf, chan, offset_end - 1,
- commit_count, endidx, handle);
+ commit_count, endidx, handle
, ctx->tsc
);
/*
* Update used size at each commit. It's needed only for extracting
* ring_buffer buffers from vmcore, after crash.
*/
/*
* Update used size at each commit. It's needed only for extracting
* ring_buffer buffers from vmcore, after crash.
*/
- lib_ring_buffer_write_commit_counter(config, buf, chan, endidx,
- ctx->buf_offset, commit_count,
- ctx->slot_size, handle);
+ lib_ring_buffer_write_commit_counter(config, buf, chan,
+ offset_end, commit_count, handle, cc_hot);
}
/**
}
/**
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