#include "frontend.h"
#include <urcu-bp.h>
#include <urcu/compiler.h>
+#include "rseq.h"
+
+static inline
+int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *config)
+{
+ return lttng_ust_get_cpu();
+}
/**
- * lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit.
+ * lib_ring_buffer_begin - 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
* section.
*/
static inline
-int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *config)
+int lib_ring_buffer_begin(const struct lttng_ust_lib_ring_buffer_config *config)
{
- int cpu, nesting;
+ int nesting;
- rcu_read_lock();
- cpu = lttng_ust_get_cpu();
nesting = ++URCU_TLS(lib_ring_buffer_nesting);
cmm_barrier();
if (caa_unlikely(nesting > 4)) {
WARN_ON_ONCE(1);
URCU_TLS(lib_ring_buffer_nesting)--;
- rcu_read_unlock();
return -EPERM;
- } else
- return cpu;
+ }
+ return 0;
}
/**
- * lib_ring_buffer_put_cpu - Follows ring buffer reserve/commit.
+ * lib_ring_buffer_end - Follows ring buffer reserve/commit.
*/
static inline
-void lib_ring_buffer_put_cpu(const struct lttng_ust_lib_ring_buffer_config *config)
+void lib_ring_buffer_end(const struct lttng_ust_lib_ring_buffer_config *config)
{
cmm_barrier();
URCU_TLS(lib_ring_buffer_nesting)--; /* TLS */
- rcu_read_unlock();
}
/*
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);
- 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;
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);
+ struct lttng_rseq_state rseq_state;
+
+ if (caa_likely(ctx->ctx_len
+ >= sizeof(struct lttng_ust_lib_ring_buffer_ctx))) {
+ rseq_state = ctx->rseq_state;
+ } else {
+ rseq_state.cpu_id = -2;
+ }
+
+ if (caa_unlikely(!cc_hot))
+ return;
/*
* 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
*/
cmm_smp_wmb();
- v_add(config, ctx->slot_size, &shmp_index(handle, buf->commit_hot, endidx)->cc);
+ if (caa_likely(rseq_state.cpu_id >= 0)) {
+ unsigned long newv;
+
+ newv = cc_hot->cc_rseq + ctx->slot_size;
+ if (caa_likely(__rseq_finish(NULL, 0, NULL, NULL, 0,
+ (intptr_t *)&cc_hot->cc_rseq,
+ (intptr_t) newv,
+ rseq_state, RSEQ_FINISH_SINGLE, false)))
+ goto add_done;
+ }
+ v_add(config, ctx->slot_size, &cc_hot->cc);
+add_done:
/*
* commit count read can race with concurrent OOO commit count updates.
* 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);
+ commit_count += cc_hot->cc_rseq;
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.
*/
- 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);
}
/**
projects / lttng-ust.git / blobdiff