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FAILED: patch "[PATCH] platform/x86/intel/tpmi/plr: Prevent fault during unbind" failed to apply to 6.12-stable tree

PATCH [email protected] 1 participant 1 message May 20

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The patch below does not apply to the 6.12-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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 14473e8c4e97d51eff9b2f384ae696f7a32f182b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026052017-unified-copilot-2eb5@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 14473e8c4e97d51eff9b2f384ae696f7a32f182b Mon Sep 17 00:00:00 2001
From: Srinivas Pandruvada <[email protected]>
Date: Thu, 30 Apr 2026 08:11:03 -0700
Subject: [PATCH] platform/x86/intel/tpmi/plr: Prevent fault during unbind
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This driver faults when intel vsec driver is unbound from PCI driver interface. For example:

echo 0000:00:03.1 > /sys/bus/pci/drivers/intel_vsec/unbind

This is caused by accessing plr->dbgfs_dir after vsec_tpmi driver is removed. Here vsec_tpmi driver is the parent. On unbind, the parent device remove callback is called first which here will remove debugfs interface. Hence plr->dbgfs_dir is no longer valid.

Register notifier for TPMI_CORE_EXIT and make this pointer to NULL, so that debugfs_remove_recursive() is not called with bad plr->dbgfs_dir pointer.

After notifier is returned the vsec_tpmi driver will call remove debugfs by calling debugfs_remove_recursive().

Fixes 811f67c51636 ("platform/x86/intel/tpmi: Add new auxiliary driver for performance limits")
Signed-off-by Srinivas Pandruvada <[email protected]>
Cc [email protected]
Link https://patch.msgid.link/[email protected] open here
Reviewed-by Ilpo Järvinen <[email protected]>
Signed-off-by Ilpo Järvinen <[email protected]>
drivers/platform/x86/intel/plr_tpmi.c +43 -2
index 05727169f49c..8faecc311038 100644
@@ -22,6 +22,7 @@
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/mutex.h>
+#include <linux/notifier.h>
 #include <linux/seq_file.h>
 #include <linux/sprintf.h>
 #include <linux/types.h>

@@ -60,6 +61,8 @@ struct tpmi_plr {
 	struct tpmi_plr_die *die_info;
 	int num_dies;
 	struct auxiliary_device *auxdev;
+	struct notifier_block nb;
+	struct mutex lock;	/* Protect access to dbgfs_dir */
 };
 
 static const char * const plr_coarse_reasons[] = {

@@ -255,6 +258,30 @@ static ssize_t plr_status_write(struct file *filp, const char __user *ubuf,
 }
 DEFINE_SHOW_STORE_ATTRIBUTE(plr_status);
 
+static int intel_plr_notify(struct notifier_block *self, unsigned long action, void *data)
+{
+	struct tpmi_plr *plr = container_of(self, struct tpmi_plr, nb);
+
+	if (action == TPMI_CORE_EXIT) {
+		guard(mutex)(&plr->lock);
+		plr->dbgfs_dir = NULL;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int intel_plr_register_notifier(struct notifier_block *nb)
+{
+	nb->notifier_call = intel_plr_notify;
+	nb->priority = 0;
+	return tpmi_register_notifier(nb);
+}
+
+static void intel_plr_unregister_notifier(struct notifier_block *nb)
+{
+	tpmi_unregister_notifier(nb);
+}
+
 static int intel_plr_probe(struct auxiliary_device *auxdev, const struct auxiliary_device_id *id)
 {
 	struct oobmsm_plat_info *plat_info;

@@ -282,10 +309,18 @@ static int intel_plr_probe(struct auxiliary_device *auxdev, const struct auxilia
 	if (!plr)
 		return -ENOMEM;
 
+	err = devm_mutex_init(&auxdev->dev, &plr->lock);
+	if (err)
+		return err;
+
+	intel_plr_register_notifier(&plr->nb);
+
 	plr->die_info = devm_kcalloc(&auxdev->dev, num_resources, sizeof(*plr->die_info),
 				     GFP_KERNEL);
-	if (!plr->die_info)
-		return -ENOMEM;
+	if (!plr->die_info) {
+		err = -ENOMEM;
+		goto err_notify;
+	}
 
 	plr->num_dies = num_resources;
 	plr->dbgfs_dir = debugfs_create_dir("plr", dentry);

@@ -326,6 +361,9 @@ static int intel_plr_probe(struct auxiliary_device *auxdev, const struct auxilia
 
 err:
 	debugfs_remove_recursive(plr->dbgfs_dir);
+err_notify:
+	intel_plr_unregister_notifier(&plr->nb);
+
 	return err;
 }
 

@@ -333,6 +371,9 @@ static void intel_plr_remove(struct auxiliary_device *auxdev)
 {
 	struct tpmi_plr *plr = auxiliary_get_drvdata(auxdev);
 
+	intel_plr_unregister_notifier(&plr->nb);
+
+	guard(mutex)(&plr->lock);
 	debugfs_remove_recursive(plr->dbgfs_dir);
 }