On Tue, 24 Dec 2019 11:02:10 +0100, Takashi Sakamoto wrote: > > On Mon, Dec 23, 2019 at 04:03:53PM +0100, Takashi Iwai wrote: > > On Mon, 23 Dec 2019 10:33:47 +0100, > > Takashi Sakamoto wrote: > > > > > > A design of ALSA control core allows applications to execute three > > > operations for TLV feature; read, write and command. Furthermore, it > > > allows driver developers to process the operations by two ways; allocated > > > array or callback function. In the former, read operation is just allowed, > > > thus developers uses the latter when device driver supports variety of > > > models or the target model is expected to dynamically change information > > > stored in TLV container. > > > > > > The core also allows applications to lock any element so that the other > > > applications can't perform write operation to the element for element > > > value and TLV information. When the element is locked, write and command > > > operation for TLV information are prohibited as well as element value. > > > Any read operation should be allowed in the case. > > > > > > At present, when an element has callback function for TLV information, > > > TLV read operation returns EPERM if the element is locked. On the > > > other hand, the read operation is success when an element has allocated > > > array for TLV information. In both cases, read operation is success for > > > element value expectedly. > > > > > > This commit fixes the bug. This change can be backported to v4.14 > > > kernel or later. > > > > The patch looks good but your sign-off is missing... > > Oops, I was in the festive mood... > > Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx> > > Besides, let us backport this patch to older kernels? As long as I > investigate, this bug exists since v2.6.19 kernel, in which TLV feature > was firstly introduced and extended[1]. When I worked for refactoring to > control core in v4,14 kernel, the bug remains kept as is[2]. > > It's possible to apply this patch to the longterm v4.14.160 kernel. But > when fixing this bug for the older kernels. we need to prepare an > alternative patch. In my opinion, the disadvantage of the bug is not so > critical, thus it's reasonable to abandon the older kernels. I don't think we need a stable backport. It's no regression, as you pointed, and nothing leading to a serious problem like a crash. So I merged now to for-next branch for 5.6 branch without Cc-to-stable. Also corrected the comment in C style as Jaroslav suggested, too. thanks, Takashi > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/commit/?h=8aa9b586e4209 > [2] https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/commit/?h=450296f305f13 > > > Regards > > Takashi Sakamoto > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
