On Sun, May 13, 2012 at 07:56:01PM +0300, Dan Carpenter wrote: > On Fri, May 11, 2012 at 05:17:17PM -0700, Anton Vorontsov 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. > > > > Say if you did notice it, what would that look like? It's just that > something gets lost instead of written to the screen right? Yep. Suppose the ring buffer size is 4096 bytes, when somebody tries to write a data in a 2000 bytes chunk, the first write will succeed (buffer size will be 2000), but the second now 3000-bytes write will left the size equal to 2000, instead of clamping it to 4096. When we had a large buffer but a small writes (e.g. ram_console usage scenario), this is almost unnoticeable. But when we started using large writes the bug showed up. Thanks, -- Anton Vorontsov Email: cbouatmailru@xxxxxxxxx _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
