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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Level: X-Spam-Flag: NO X-Rspamd-Queue-Id: AEFA21F818 X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; FREEMAIL_TO(0.00)[gmail.com,linux.intel.com,kernel.org,ffwll.ch]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_SEVEN(0.00)[8]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[147ba789658184f0ce04]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:mid] X-Spam-Score: -3.01 Hi Am 02.10.25 um 04:57 schrieb Chintan Patel: > When wait_event_timeout() in drm_wait_one_vblank() times out, the > current WARN can cause unnecessary kernel panics in environments > with panic_on_warn set (e.g. CI, fuzzing). These timeouts can happen > under scheduler pressure or from invalid userspace calls, so they are > not always a kernel bug. > > Replace the WARN with drm_dbg_kms() messages that provide useful > context (last and current vblank counters) without crashing the > system. Developers can still enable drm.debug to diagnose genuine > problems. > > Reported-by: syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=147ba789658184f0ce04 > Tested-by: syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com > > Signed-off-by: Chintan Patel There should be no empty lines among those tags > > v2: > - Drop unnecessary in-code comment (suggested by Thomas Zimmermann) > - Remove else branch, only log timeout case > --- > drivers/gpu/drm/drm_vblank.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > index 46f59883183d..a94570668cba 100644 > --- a/drivers/gpu/drm/drm_vblank.c > +++ b/drivers/gpu/drm/drm_vblank.c > @@ -1289,7 +1289,7 @@ void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe) > { > struct drm_vblank_crtc *vblank = drm_vblank_crtc(dev, pipe); > int ret; > - u64 last; > + u64 last, curr; > > if (drm_WARN_ON(dev, pipe >= dev->num_crtcs)) > return; > @@ -1305,7 +1305,12 @@ void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe) > last != drm_vblank_count(dev, pipe), > msecs_to_jiffies(100)); > > - drm_WARN(dev, ret == 0, "vblank wait timed out on crtc %i\n", pipe); > + curr = drm_vblank_count(dev, pipe); Please don't call drm_vblank_count() here. It's not necessary for regular operation. Simply keep the debug message as-is. > + > + if (ret == 0) { "if (!ret)" is the preferred style. > + drm_dbg_kms(dev, "WAIT_VBLANK: timeout crtc=%d, last=%llu, curr=%llu\n", > + pipe, last, curr); Aligning the pipe argument with dev from the previous line is the preferred style. Best regards Thomas > + } > > drm_vblank_put(dev, pipe); > } -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)