| Message ID | 1456434600-4185759-1-git-send-email-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi On Thu, Feb 25, 2016 at 10:09 PM, Arnd Bergmann <arnd@arndb.de> wrote: > gcc warns about the timestamp in drm_wait_vblank being possibly > used without an initialization: > > drivers/gpu/drm/drm_irq.c: In function 'drm_wait_vblank': > drivers/gpu/drm/drm_irq.c:1755:28: warning: 'now.tv_usec' may be used uninitialized in this function [-Wmaybe-uninitialized] > vblwait->reply.tval_usec = now.tv_usec; > drivers/gpu/drm/drm_irq.c:1754:27: warning: 'now.tv_sec' may be used uninitialized in this function [-Wmaybe-uninitialized] > vblwait->reply.tval_sec = now.tv_sec; > > This can happen if drm_vblank_count_and_time() returns 0 in its > error path. To sanitize the error case, I'm changing that function > to return a zero timestamp when it fails. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: e6ae8687a87b ("drm: idiot-proof vblank") > --- > drivers/gpu/drm/drm_irq.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > I'm going through the maybe-unused warnings in randconfig builds, this one is > apparently not a false positive, although it only happens if something > else has already gone wrong. > > Originally sent out on Jan 13, but I received no reply, so resending now. > > diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c > index 881c5a6c180c..6f41ddfbe061 100644 > --- a/drivers/gpu/drm/drm_irq.c > +++ b/drivers/gpu/drm/drm_irq.c > @@ -997,8 +997,10 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, > int count = DRM_TIMESTAMP_MAXRETRIES; > u32 cur_vblank; > > - if (WARN_ON(pipe >= dev->num_crtcs)) > + if (WARN_ON(pipe >= dev->num_crtcs)) { > + *vblanktime = (struct timeval) { 0 }; The '0' is redundant. Anyway, this is: Reviewed-by: David Herrmann <dh.herrmann@gmail.com> (CC: Daniel, for drm-misc) Thanks David > return 0; > + } > > /* > * Vblank timestamps are read lockless. To ensure consistency the vblank > -- > 2.7.0 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 881c5a6c180c..6f41ddfbe061 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -997,8 +997,10 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, int count = DRM_TIMESTAMP_MAXRETRIES; u32 cur_vblank; - if (WARN_ON(pipe >= dev->num_crtcs)) + if (WARN_ON(pipe >= dev->num_crtcs)) { + *vblanktime = (struct timeval) { 0 }; return 0; + } /* * Vblank timestamps are read lockless. To ensure consistency the vblank
gcc warns about the timestamp in drm_wait_vblank being possibly used without an initialization: drivers/gpu/drm/drm_irq.c: In function 'drm_wait_vblank': drivers/gpu/drm/drm_irq.c:1755:28: warning: 'now.tv_usec' may be used uninitialized in this function [-Wmaybe-uninitialized] vblwait->reply.tval_usec = now.tv_usec; drivers/gpu/drm/drm_irq.c:1754:27: warning: 'now.tv_sec' may be used uninitialized in this function [-Wmaybe-uninitialized] vblwait->reply.tval_sec = now.tv_sec; This can happen if drm_vblank_count_and_time() returns 0 in its error path. To sanitize the error case, I'm changing that function to return a zero timestamp when it fails. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: e6ae8687a87b ("drm: idiot-proof vblank") --- drivers/gpu/drm/drm_irq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) I'm going through the maybe-unused warnings in randconfig builds, this one is apparently not a false positive, although it only happens if something else has already gone wrong. Originally sent out on Jan 13, but I received no reply, so resending now.