On 01/27/2016 09:57 PM, Matthias Schwarzott wrote: > Am 27.01.2016 um 13:08 schrieb Hans Verkuil: >> The vb2_thread implementation was made generic and was moved from >> videobuf2-v4l2.c to videobuf2-core.c in commit af3bac1a. Unfortunately >> that clearly was never tested since it broke read() causing NULL address >> references. >> >> The root cause was confused handling of vb2_buffer vs v4l2_buffer (the pb >> pointer in various core functions). >> >> The v4l2_buffer no longer exists after moving the code into the core and >> it is no longer needed. However, the vb2_thread code passed a pointer to >> a vb2_buffer to the core functions were a v4l2_buffer pointer was expected >> and vb2_thread expected that the vb2_buffer fields would be filled in >> correctly. >> >> This is obviously wrong since v4l2_buffer != vb2_buffer. Note that the >> pb pointer is a void pointer, so no type-checking took place. >> >> This patch fixes this problem: >> >> 1) allow pb to be NULL for vb2_core_(d)qbuf. The vb2_thread code will use >> a NULL pointer here since they don't care about v4l2_buffer anyway. >> 2) let vb2_core_dqbuf pass back the index of the received buffer. This is >> all vb2_thread needs: this index is the index into the q->bufs array >> and vb2_thread just gets the vb2_buffer from there. >> 3) the fileio->b pointer (that originally contained a v4l2_buffer) is >> removed altogether since it is no longer needed. >> >> Tested with vivid and the cobalt driver. >> >> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> >> Tested-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> >> Reported-by: Matthias Schwarzott <zzam@xxxxxxxxxx> > > Hi Hans! > > Thank you for this patch. > I gave this patch a try on the latest sources from > git://linuxtv.org/media_tree.git > > Compiled for kernel 4.2.8 with media_build. > > Now it no longer oopses. Good. > It tunes fine (according to femon), but I still do not get a > picture/dvbtraffic reports nothing. I will try to do a DVB test tomorrow. I can't spend too much time on it so if I can't reproduce it I'll probably ask Mauro to take a look. After tomorrow it will take at least a week before I have another chance of testing this due to traveling. Regards, Hans > > Regards > Matthias > > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
