Patch "rcuscale: Do a proper cleanup if kfree_scale_init() fails" has been added to the 6.12-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    rcuscale: Do a proper cleanup if kfree_scale_init() fails

to the 6.12-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:
     rcuscale-do-a-proper-cleanup-if-kfree_scale_init-fai.patch
and it can be found in the queue-6.12 subdirectory.

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



commit 0e3a999c7bad23af102e41fffd306191c2947743
Author: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Date:   Wed Nov 13 12:00:08 2024 +0100

    rcuscale: Do a proper cleanup if kfree_scale_init() fails
    
    [ Upstream commit 812a1c3b9f7c36d9255f0d29d0a3d324e2f52321 ]
    
    A static analyzer for C, Smatch, reports and triggers below
    warnings:
    
       kernel/rcu/rcuscale.c:1215 rcu_scale_init()
       warn: inconsistent returns 'global &fullstop_mutex'.
    
    The checker complains about, we do not unlock the "fullstop_mutex"
    mutex, in case of hitting below error path:
    
    <snip>
    ...
        if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
            pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
            WARN_ON_ONCE(1);
            return -1;
            ^^^^^^^^^^
    ...
    <snip>
    
    it happens because "-1" is returned right away instead of
    doing a proper unwinding.
    
    Fix it by jumping to "unwind" label instead of returning -1.
    
    Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
    Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
    Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@xxxxxxx>
    Closes: https://lore.kernel.org/rcu/ZxfTrHuEGtgnOYWp@pc636/T/
    Fixes: 084e04fff160 ("rcuscale: Add laziness and kfree tests")
    Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
    Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index 6d37596deb1f1..d360fa44b234d 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -890,13 +890,15 @@ kfree_scale_init(void)
 		if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
 			pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
 			WARN_ON_ONCE(1);
-			return -1;
+			firsterr = -1;
+			goto unwind;
 		}
 
 		if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start > 3 * HZ)) {
 			pr_alert("ERROR: call_rcu() CBs are being too lazy!\n");
 			WARN_ON_ONCE(1);
-			return -1;
+			firsterr = -1;
+			goto unwind;
 		}
 	}