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[158.222.149.228]) by smtp.gmail.com with ESMTPSA id x26-v6sm12830244qth.15.2018.09.03.14.18.19 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 03 Sep 2018 14:18:19 -0700 (PDT) Date: Tue, 4 Sep 2018 00:18:17 +0300 From: Haneen Mohammed To: dri-devel@lists.freedesktop.org Subject: [PATCH v2] drm/vkms: Fix race condition around accessing frame number Message-ID: <20180903211743.GA2773@haneenDRM> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-Mailman-Approved-At: Tue, 04 Sep 2018 07:06:03 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: seanpaul@chromium.org, rodrigosiqueiramelo@gmail.com, hamohammed.sa@gmail.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP crtc_state is accessed by both vblank_handle() and the ordered work_struct handle vkms_crc_work_handle() to retrieve and or update the frame number for computed CRC. Since work_struct can fail, add frame_end to account for missing frame numbers. Use (frame_[start/end]) for synchronization between hrtimer callback and ordered work_struct handle. This patch passes the following subtests from igt kms_pipe_crc_basic test: bad-source, read-crc-pipe-A, read-crc-pipe-A-frame-sequence, nonblocking-crc-pipe-A, nonblocking-crc-pipe-A-frame-sequence Signed-off-by: Haneen Mohammed --- v2: - use u64 with spinlock instead of atomic_t - add out label for common exit routine @vkms_crc_work_handle() drivers/gpu/drm/vkms/vkms_crc.c | 36 ++++++++++++++++++++++++++++++-- drivers/gpu/drm/vkms/vkms_crtc.c | 16 ++++++++++++-- drivers/gpu/drm/vkms/vkms_drv.h | 8 +++++-- 3 files changed, 54 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c index ed47d67cecd6..68db42f15086 100644 --- a/drivers/gpu/drm/vkms/vkms_crc.c +++ b/drivers/gpu/drm/vkms/vkms_crc.c @@ -34,6 +34,15 @@ static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data) return crc; } +/** + * vkms_crc_work_handle - ordered work_struct to compute CRC + * + * @work: work_struct + * + * Work handler for computing CRCs. work_struct scheduled in + * an ordered workqueue that's periodically scheduled to run by + * _vblank_handle() and flushed at vkms_atomic_crtc_destroy_state(). + */ void vkms_crc_work_handle(struct work_struct *work) { struct vkms_crtc_state *crtc_state = container_of(work, @@ -45,8 +54,18 @@ void vkms_crc_work_handle(struct work_struct *work) output); struct vkms_crc_data *primary_crc = NULL; struct drm_plane *plane; - u32 crc32 = 0; + u64 frame_start, frame_end; + unsigned long flags; + + spin_lock_irqsave(&out->state_lock, flags); + frame_start = crtc_state->frame_start; + frame_end = crtc_state->frame_end; + spin_unlock_irqrestore(&out->state_lock, flags); + + /* _vblank_handle() hasn't updated frame_start yet */ + if (!frame_start || frame_start == frame_end) + goto out; drm_for_each_plane(plane, &vdev->drm) { struct vkms_plane_state *vplane_state; @@ -67,7 +86,20 @@ void vkms_crc_work_handle(struct work_struct *work) if (primary_crc) crc32 = _vkms_get_crc(primary_crc); - drm_crtc_add_crc_entry(crtc, true, crtc_state->n_frame, &crc32); + frame_end = drm_crtc_accurate_vblank_count(crtc); + + /* queue_work can fail to schedule crc_work; add crc for + * missing frames + */ + while (frame_start <= frame_end) + drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32); + +out: + /* to avoid using the same value for frame number again */ + spin_lock_irqsave(&out->state_lock, flags); + crtc_state->frame_end = frame_end; + crtc_state->frame_start = 0; + spin_unlock_irqrestore(&out->state_lock, flags); } static int vkms_crc_parse_source(const char *src_name, bool *enabled) diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c index 9d0b1a325a78..177bbcb38306 100644 --- a/drivers/gpu/drm/vkms/vkms_crtc.c +++ b/drivers/gpu/drm/vkms/vkms_crtc.c @@ -22,8 +22,19 @@ static void _vblank_handle(struct vkms_output *output) DRM_ERROR("vkms failure on handling vblank"); if (state && output->crc_enabled) { - state->n_frame = drm_crtc_accurate_vblank_count(crtc); - queue_work(output->crc_workq, &state->crc_work); + u64 frame = drm_crtc_accurate_vblank_count(crtc); + + /* update frame_start only if a queued vkms_crc_work_handle() + * has read the data + */ + spin_lock(&output->state_lock); + if (!state->frame_start) + state->frame_start = frame; + spin_unlock(&output->state_lock); + + ret = queue_work(output->crc_workq, &state->crc_work); + if (!ret) + DRM_WARN("failed to queue vkms_crc_work_handle"); } spin_unlock(&output->lock); @@ -211,6 +222,7 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc, drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs); spin_lock_init(&vkms_out->lock); + spin_lock_init(&vkms_out->state_lock); vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0); diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h index 2017a2ccc43d..80af6d3a65e7 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.h +++ b/drivers/gpu/drm/vkms/vkms_drv.h @@ -39,12 +39,14 @@ struct vkms_plane_state { * vkms_crtc_state - Driver specific CRTC state * @base: base CRTC state * @crc_work: work struct to compute and add CRC entries - * @n_frame: frame number for computed CRC + * @n_frame_start: start frame number for computed CRC + * @n_frame_end: end frame number for computed CRC */ struct vkms_crtc_state { struct drm_crtc_state base; struct work_struct crc_work; - unsigned int n_frame; + u64 frame_start; + u64 frame_end; }; struct vkms_output { @@ -59,6 +61,8 @@ struct vkms_output { struct workqueue_struct *crc_workq; /* protects concurrent access to crc_data */ spinlock_t lock; + /* protects concurrent access to crtc_state */ + spinlock_t state_lock; }; struct vkms_device {