/**
* 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
{
int cpu, 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;
{
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(uatomic_read(&buf->record_disabled)))
return -EAGAIN;
ctx->buf = buf;