| Message ID | 20120512001717.GB14782@lizard |
|---|---|
| State | Accepted |
| Commit | 484dd30e016eb425b0de871357fff2c9bb93be45 |
| Headers | show |
On Fri, May 11, 2012 at 5:17 PM, Anton Vorontsov <anton.vorontsov@linaro.org> wrote: > 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); > > -- > 1.7.9.2 > Acked-by: Colin Cross <ccross@android.com> This is a bug fix for a bug introduced in 3.4-rc1, it should go into 3.4 if there is another rc.
On Sun, May 13, 2012 at 08:23:58PM -0700, Colin Cross wrote: > On Fri, May 11, 2012 at 5:17 PM, Anton Vorontsov > <anton.vorontsov@linaro.org> wrote: > > 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); > > > > -- > > 1.7.9.2 > > > > Acked-by: Colin Cross <ccross@android.com> > > This is a bug fix for a bug introduced in 3.4-rc1, it should go into > 3.4 if there is another rc. I'll queue it up for 3.4.1. thanks, greg k-h
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);
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(-)