Patch "devlink: Hold devlink lock on health reporter dump get" has been added to the 6.5-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    devlink: Hold devlink lock on health reporter dump get

to the 6.5-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     devlink-hold-devlink-lock-on-health-reporter-dump-ge.patch
and it can be found in the queue-6.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 85941b6e651c76f77fe5536a6ad22ae4f8312e69
Author: Moshe Shemesh <moshe@xxxxxxxxxx>
Date:   Thu Oct 5 15:50:16 2023 +0300

    devlink: Hold devlink lock on health reporter dump get
    
    [ Upstream commit aba0e909dc20eceb1de985474af459f82e7b0b82 ]
    
    Devlink health dump get callback should take devlink lock as any other
    devlink callback. Otherwise, since devlink_mutex was removed, this
    callback is not protected from a race of the reporter being destroyed
    while handling the callback.
    
    Add devlink lock to the callback and to any call for
    devlink_health_do_dump(). This should be safe as non of the drivers dump
    callback implementation takes devlink lock.
    
    As devlink lock is added to any callback of dump, the reporter dump_lock
    is now redundant and can be removed.
    
    Fixes: d3efc2a6a6d8 ("net: devlink: remove devlink_mutex")
    Signed-off-by: Moshe Shemesh <moshe@xxxxxxxxxx>
    Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
    Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@xxxxxxxxx>
    Link: https://lore.kernel.org/r/1696510216-189379-1-git-send-email-moshe@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/devlink/health.c b/net/devlink/health.c
index 194340a8bb863..8c6a2e5140d4d 100644
--- a/net/devlink/health.c
+++ b/net/devlink/health.c
@@ -58,7 +58,6 @@ struct devlink_health_reporter {
 	struct devlink *devlink;
 	struct devlink_port *devlink_port;
 	struct devlink_fmsg *dump_fmsg;
-	struct mutex dump_lock; /* lock parallel read/write from dump buffers */
 	u64 graceful_period;
 	bool auto_recover;
 	bool auto_dump;
@@ -125,7 +124,6 @@ __devlink_health_reporter_create(struct devlink *devlink,
 	reporter->graceful_period = graceful_period;
 	reporter->auto_recover = !!ops->recover;
 	reporter->auto_dump = !!ops->dump;
-	mutex_init(&reporter->dump_lock);
 	return reporter;
 }
 
@@ -226,7 +224,6 @@ EXPORT_SYMBOL_GPL(devlink_health_reporter_create);
 static void
 devlink_health_reporter_free(struct devlink_health_reporter *reporter)
 {
-	mutex_destroy(&reporter->dump_lock);
 	if (reporter->dump_fmsg)
 		devlink_fmsg_free(reporter->dump_fmsg);
 	kfree(reporter);
@@ -609,10 +606,10 @@ int devlink_health_report(struct devlink_health_reporter *reporter,
 	}
 
 	if (reporter->auto_dump) {
-		mutex_lock(&reporter->dump_lock);
+		devl_lock(devlink);
 		/* store current dump of current error, for later analysis */
 		devlink_health_do_dump(reporter, priv_ctx, NULL);
-		mutex_unlock(&reporter->dump_lock);
+		devl_unlock(devlink);
 	}
 
 	if (!reporter->auto_recover)
@@ -1246,7 +1243,7 @@ int devlink_nl_cmd_health_reporter_diagnose_doit(struct sk_buff *skb,
 }
 
 static struct devlink_health_reporter *
-devlink_health_reporter_get_from_cb(struct netlink_callback *cb)
+devlink_health_reporter_get_from_cb_lock(struct netlink_callback *cb)
 {
 	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
 	struct devlink_health_reporter *reporter;
@@ -1256,10 +1253,12 @@ devlink_health_reporter_get_from_cb(struct netlink_callback *cb)
 	devlink = devlink_get_from_attrs_lock(sock_net(cb->skb->sk), attrs);
 	if (IS_ERR(devlink))
 		return NULL;
-	devl_unlock(devlink);
 
 	reporter = devlink_health_reporter_get_from_attrs(devlink, attrs);
-	devlink_put(devlink);
+	if (!reporter) {
+		devl_unlock(devlink);
+		devlink_put(devlink);
+	}
 	return reporter;
 }
 
@@ -1268,16 +1267,20 @@ int devlink_nl_cmd_health_reporter_dump_get_dumpit(struct sk_buff *skb,
 {
 	struct devlink_nl_dump_state *state = devlink_dump_state(cb);
 	struct devlink_health_reporter *reporter;
+	struct devlink *devlink;
 	int err;
 
-	reporter = devlink_health_reporter_get_from_cb(cb);
+	reporter = devlink_health_reporter_get_from_cb_lock(cb);
 	if (!reporter)
 		return -EINVAL;
 
-	if (!reporter->ops->dump)
+	devlink = reporter->devlink;
+	if (!reporter->ops->dump) {
+		devl_unlock(devlink);
+		devlink_put(devlink);
 		return -EOPNOTSUPP;
+	}
 
-	mutex_lock(&reporter->dump_lock);
 	if (!state->idx) {
 		err = devlink_health_do_dump(reporter, NULL, cb->extack);
 		if (err)
@@ -1293,7 +1296,8 @@ int devlink_nl_cmd_health_reporter_dump_get_dumpit(struct sk_buff *skb,
 	err = devlink_fmsg_dumpit(reporter->dump_fmsg, skb, cb,
 				  DEVLINK_CMD_HEALTH_REPORTER_DUMP_GET);
 unlock:
-	mutex_unlock(&reporter->dump_lock);
+	devl_unlock(devlink);
+	devlink_put(devlink);
 	return err;
 }
 
@@ -1310,9 +1314,7 @@ int devlink_nl_cmd_health_reporter_dump_clear_doit(struct sk_buff *skb,
 	if (!reporter->ops->dump)
 		return -EOPNOTSUPP;
 
-	mutex_lock(&reporter->dump_lock);
 	devlink_health_dump_clear(reporter);
-	mutex_unlock(&reporter->dump_lock);
 	return 0;
 }