[PATCH v5 20/27] drm: Scope all DRM IOCTLs with drm_dev_enter/exit

[Andrey Grodzovsky]

With this calling drm_dev_unplug will flush and block
all in flight IOCTLs

Also, add feature such that if device supports graceful unplug
we enclose entire IOCTL in SRCU critical section.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
---
 drivers/gpu/drm/drm_ioctl.c | 15 +++++++++++++--
 include/drm/drm_drv.h       |  6 ++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index d273d1a8603a..5882ef2183bb 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -815,7 +815,7 @@ long drm_ioctl(struct file *filp,
 	const struct drm_ioctl_desc *ioctl = NULL;
 	drm_ioctl_t *func;
 	unsigned int nr = DRM_IOCTL_NR(cmd);
-	int retcode = -EINVAL;
+	int idx, retcode = -EINVAL;
 	char stack_kdata[128];
 	char *kdata = NULL;
 	unsigned int in_size, out_size, drv_size, ksize;
@@ -884,7 +884,18 @@ long drm_ioctl(struct file *filp,
 	if (ksize > in_size)
 		memset(kdata + in_size, 0, ksize - in_size);
 
-	retcode = drm_ioctl_kernel(filp, func, kdata, ioctl->flags);
+	if (drm_core_check_feature(dev, DRIVER_HOTUNPLUG_SUPPORT)) {
+		if (drm_dev_enter(dev, &idx)) {
+			retcode = drm_ioctl_kernel(filp, func, kdata, ioctl->flags);
+			drm_dev_exit(idx);
+		} else {
+			retcode = -ENODEV;
+			goto err_i1;
+		}
+	} else {
+		retcode = drm_ioctl_kernel(filp, func, kdata, ioctl->flags);
+	}
+
 	if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
 		retcode = -EFAULT;
 
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index b439ae1921b8..63e05cec46c1 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -94,6 +94,12 @@ enum drm_driver_feature {
 	 * synchronization of command submission.
 	 */
 	DRIVER_SYNCOBJ_TIMELINE         = BIT(6),
+	/**
+	 * @DRIVER_NO_HOTUNPLUG_SUPPORT:
+	 *
+	 * Driver support gracefull remove.
+	 */
+	DRIVER_HOTUNPLUG_SUPPORT         = BIT(7),
 
 	/* IMPORTANT: Below are all the legacy flags, add new ones above. */
 
-- 
2.25.1