This is a longstanding bug, almost unnoticeable when calling persistent_ram_write() for small buffers.
But when called for large data buffers, the write routine behaves incorrectly, as the size may never update: instead of clamping the size to the maximum buffer size, buffer_size_add_clamp() returns an error (which is never checked by the write routine, btw).
To fix this, we now use buffer_size_add() that actually clamps the size to the max value.
Also remove buffer_size_add_clamp(), it is no longer needed.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- drivers/staging/android/persistent_ram.c | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-)
diff --git a/drivers/staging/android/persistent_ram.c b/drivers/staging/android/persistent_ram.c index 12444fd..13a12bc 100644 --- a/drivers/staging/android/persistent_ram.c +++ b/drivers/staging/android/persistent_ram.c @@ -79,23 +79,6 @@ static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a) } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); }
-/* increase the size counter, retuning an error if it hits the max size */ -static inline ssize_t buffer_size_add_clamp(struct persistent_ram_zone *prz, - size_t a) -{ - size_t old; - size_t new; - - do { - old = atomic_read(&prz->buffer->size); - new = old + a; - if (new > prz->buffer_size) - return -ENOMEM; - } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); - - return 0; -} - static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, uint8_t *data, size_t len, uint8_t *ecc) { @@ -300,7 +283,7 @@ int notrace persistent_ram_write(struct persistent_ram_zone *prz, c = prz->buffer_size; }
- buffer_size_add_clamp(prz, c); + buffer_size_add(prz, c);
start = buffer_start_add(prz, c);