FAILED: patch "[PATCH] drm/vc4: Stop the active perfmon before being destroyed" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x 0b2ad4f6f2bec74a5287d96cb2325a5e11706f22
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024101431-able-caress-7fe5@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

0b2ad4f6f2be ("drm/vc4: Stop the active perfmon before being destroyed")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0b2ad4f6f2bec74a5287d96cb2325a5e11706f22 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ADra=20Canal?= <[email protected]>
Date: Fri, 4 Oct 2024 09:36:00 -0300
Subject: [PATCH] drm/vc4: Stop the active perfmon before being destroyed
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Upon closing the file descriptor, the active performance monitor is not stopped. Although all perfmons are destroyed in vc4_perfmon_close_file(), the active performance monitor's pointer (vc4->active_perfmon) is still retained.

If we open a new file descriptor and submit a few jobs with performance monitors, the driver will attempt to stop the active performance monitor using the stale pointer in vc4->active_perfmon. However, this pointer is no longer valid because the previous process has already terminated, and all performance monitors associated with it have been destroyed and freed.

To fix this, when the active performance monitor belongs to a given process, explicitly stop it before destroying and freeing it.

index c4ac2c946238..c00a5cc2316d 100644
@@ -116,6 +116,11 @@ void vc4_perfmon_open_file(struct vc4_file *vc4file)
 static int vc4_perfmon_idr_del(int id, void *elem, void *data)
 {
 	struct vc4_perfmon *perfmon = elem;
+	struct vc4_dev *vc4 = (struct vc4_dev *)data;
+
+	/* If the active perfmon is being destroyed, stop it first */
+	if (perfmon == vc4->active_perfmon)
+		vc4_perfmon_stop(vc4, perfmon, false);
 
 	vc4_perfmon_put(perfmon);
 

@@ -130,7 +135,7 @@ void vc4_perfmon_close_file(struct vc4_file *vc4file)
 		return;
 
 	mutex_lock(&vc4file->perfmon.lock);
-	idr_for_each(&vc4file->perfmon.idr, vc4_perfmon_idr_del, NULL);
+	idr_for_each(&vc4file->perfmon.idr, vc4_perfmon_idr_del, vc4);
 	idr_destroy(&vc4file->perfmon.idr);
 	mutex_unlock(&vc4file->perfmon.lock);
 	mutex_destroy(&vc4file->perfmon.lock);