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drm/crc: Handle opening and closing crc better

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When I was doing a grep . -r /sys/kernel/debug/dri/0 I noticed a WARN
appearing when I aborted the grep with ^C.

After investigating I've also noticed that the error handling was
lacking and there are race conditions involving multiple calls to
open/close simultaneously.

Fix this by setting the opened flag first and using crc->entries to
decide when crc can be collected.

Also call unset crc source before cleaning up, this way there is
no race with a future open().

This patch has been tested with all the tests in igt with CRC in their
name.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170621110007.11674-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
[mlankhorst: Add description that this patch has been tested with IGT,
based on tomeu's feedback]
This commit is contained in:
Maarten Lankhorst 2017-06-21 13:00:07 +02:00
parent ec878c0756
commit eb42ea6d0b
1 changed files with 32 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
drivers/gpu/drm/drm_debugfs_crc.c
View File

@ -136,20 +136,37 @@ static int crtc_crc_data_count(struct drm_crtc_crc *crc)
return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
}
static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
{
kfree(crc->entries);
crc->entries = NULL;
crc->head = 0;
crc->tail = 0;
crc->values_cnt = 0;
crc->opened = false;
}
static int crtc_crc_open(struct inode *inode, struct file *filep)
{
struct drm_crtc *crtc = inode->i_private;
struct drm_crtc_crc *crc = &crtc->crc;
struct drm_crtc_crc_entry *entries = NULL;
size_t values_cnt;
int ret;
int ret = 0;
if (crc->opened)
return -EBUSY;
spin_lock_irq(&crc->lock);
if (!crc->opened)
crc->opened = true;
else
ret = -EBUSY;
spin_unlock_irq(&crc->lock);
if (ret)
return ret;
ret = crtc->funcs->set_crc_source(crtc, crc->source, &values_cnt);
if (ret)
return ret;
goto err;
if (WARN_ON(values_cnt > DRM_MAX_CRC_NR)) {
ret = -EINVAL;
@ -170,7 +187,6 @@ static int crtc_crc_open(struct inode *inode, struct file *filep)
spin_lock_irq(&crc->lock);
crc->entries = entries;
crc->values_cnt = values_cnt;
crc->opened = true;
/*
* Only return once we got a first frame, so userspace doesn't have to
@ -182,12 +198,17 @@ static int crtc_crc_open(struct inode *inode, struct file *filep)
crc->lock);
spin_unlock_irq(&crc->lock);
WARN_ON(ret);
if (ret)
goto err_disable;
return 0;
err_disable:
crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
err:
spin_lock_irq(&crc->lock);
crtc_crc_cleanup(crc);
spin_unlock_irq(&crc->lock);
return ret;
}
@ -197,17 +218,12 @@ static int crtc_crc_release(struct inode *inode, struct file *filep)
struct drm_crtc_crc *crc = &crtc->crc;
size_t values_cnt;
spin_lock_irq(&crc->lock);
kfree(crc->entries);
crc->entries = NULL;
crc->head = 0;
crc->tail = 0;
crc->values_cnt = 0;
crc->opened = false;
spin_unlock_irq(&crc->lock);
crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
spin_lock_irq(&crc->lock);
crtc_crc_cleanup(crc);
spin_unlock_irq(&crc->lock);
return 0;
}
@ -334,7 +350,7 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
spin_lock(&crc->lock);
/* Caller may not have noticed yet that userspace has stopped reading */
if (!crc->opened) {
if (!crc->entries) {
spin_unlock(&crc->lock);
return -EINVAL;
}