From: Clemens Ladisch Date: Tue, 25 May 2010 07:01:46 +0000 (+0200) Subject: ALSA: pcm: fix delta calculation at boundary wraparound X-Git-Tag: v2.6.35-rc1~253^2~2 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b406e6103baa3da85950f22d3d46d21a8da654c5;p=pandora-kernel.git ALSA: pcm: fix delta calculation at boundary wraparound In the cleanup of the hw_ptr update functions in 2.6.33, the calculation of the delta value was changed to use the modulo operator to protect against a negative difference due to the pointer wrapping around at the boundary. However, the ptr variables are unsigned, so a negative difference would result in the two complement's value which has no relation to the actual difference relative to the boundary; the result is typically some value near LONG_MAX-boundary. Furthermore, even if the modulo operation would be done with signed types, the result of a negative dividend could be negative. The invalid delta value is then caught by the following checks, but this means that the pointer update is ignored. To fix this, use a range check as in the other pointer calculations. Signed-off-by: Clemens Ladisch Cc: Signed-off-by: Takashi Iwai --- Reading git-diff-tree failed