Fix: check reference counts for overflow

[lttng-modules.git] / lib / ringbuffer / ring_buffer_frontend.c

diff --git a/lib/ringbuffer/ring_buffer_frontend.c b/lib/ringbuffer/ring_buffer_frontend.c
index ae0b9e3986267a8b79e8395d13cd23d55cc357c7..dbe52c157c71be0ec560bbc6b97dc77d1b1e27ea 100644 (file)
--- a/lib/ringbuffer/ring_buffer_frontend.c
+++ b/lib/ringbuffer/ring_buffer_frontend.c
@@ -61,6 +61,8 @@
 #include "../../wrapper/ringbuffer/iterator.h"
 #include "../../wrapper/ringbuffer/nohz.h"
 #include "../../wrapper/atomic.h"
+#include "../../wrapper/kref.h"
+#include "../../wrapper/percpu-defs.h"
 
 /*
  * Internal structure representing offsets to use at a sub-buffer switch.
@@ -498,16 +500,16 @@ static int notrace ring_buffer_tick_nohz_callback(struct notifier_block *nb,
                raw_spin_unlock(&buf->raw_tick_nohz_spinlock);
                break;
        case TICK_NOHZ_STOP:
-               spin_lock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_lock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                lib_ring_buffer_stop_switch_timer(buf);
                lib_ring_buffer_stop_read_timer(buf);
-               spin_unlock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_unlock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                break;
        case TICK_NOHZ_RESTART:
-               spin_lock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_lock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                lib_ring_buffer_start_read_timer(buf);
                lib_ring_buffer_start_switch_timer(buf);
-               spin_unlock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_unlock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                break;
        }
 
@@ -792,7 +794,10 @@ int lib_ring_buffer_open_read(struct lib_ring_buffer *buf)
 
        if (!atomic_long_add_unless(&buf->active_readers, 1, 1))
                return -EBUSY;
-       kref_get(&chan->ref);
+       if (!lttng_kref_get(&chan->ref)) {
+               atomic_long_dec(&buf->active_readers);
+               return -EOVERFLOW;
+       }
        lttng_smp_mb__after_atomic();
        return 0;
 }