FAILED: patch "[PATCH] cpu/hotplug: Fix dynstate assignment in" failed to apply to 4.19-stable tree

FAILED: patch "[PATCH] cpu/hotplug: Fix dynstate assignment in" failed to apply to 4.19-stable tree

[gregkh]

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 <stable@vger.kernel.org>.

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 932d8476399f622aa0767a4a0a9e78e5341dc0e1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024070143-petunia-runaround-2e19@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

932d8476399f ("cpu/hotplug: Fix dynstate assignment in __cpuhp_setup_state_cpuslocked()")
11bc021d1fba ("cpu/hotplug: Eliminate all kernel-doc warnings")
33c3736ec888 ("cpu/hotplug: Hide cpu_up/down()")
b99a26593b51 ("cpu/hotplug: Move bringup of secondary CPUs out of smp_init()")
d720f9860439 ("cpu/hotplug: Provide bringup_hibernate_cpu()")
0441a5597c5d ("cpu/hotplug: Create a new function to shutdown nonboot cpus")
93ef1429e556 ("cpu/hotplug: Add new {add,remove}_cpu() functions")

thanks,

greg k-h

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

From 932d8476399f622aa0767a4a0a9e78e5341dc0e1 Mon Sep 17 00:00:00 2001
From: Yuntao Wang <ytcoode@gmail.com>
Date: Wed, 15 May 2024 21:45:54 +0800
Subject: [PATCH] cpu/hotplug: Fix dynstate assignment in
 __cpuhp_setup_state_cpuslocked()

Commit 4205e4786d0b ("cpu/hotplug: Provide dynamic range for prepare
stage") added a dynamic range for the prepare states, but did not handle
the assignment of the dynstate variable in __cpuhp_setup_state_cpuslocked().

This causes the corresponding startup callback not to be invoked when
calling __cpuhp_setup_state_cpuslocked() with the CPUHP_BP_PREPARE_DYN
parameter, even though it should be.

Currently, the users of __cpuhp_setup_state_cpuslocked(), for one reason or
another, have not triggered this bug.

Fixes: 4205e4786d0b ("cpu/hotplug: Provide dynamic range for prepare stage")
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240515134554.427071-1-ytcoode@gmail.com

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 563877d6c28b..74cfdb66a9bd 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2446,7 +2446,7 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);
  * The caller needs to hold cpus read locked while calling this function.
  * Return:
  *   On success:
- *      Positive state number if @state is CPUHP_AP_ONLINE_DYN;
+ *      Positive state number if @state is CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN;
  *      0 for all other states
  *   On failure: proper (negative) error code
  */
@@ -2469,7 +2469,7 @@ int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state,
 	ret = cpuhp_store_callbacks(state, name, startup, teardown,
 				    multi_instance);
 
-	dynstate = state == CPUHP_AP_ONLINE_DYN;
+	dynstate = state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN;
 	if (ret > 0 && dynstate) {
 		state = ret;
 		ret = 0;
@@ -2500,8 +2500,8 @@ int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state,
 out:
 	mutex_unlock(&cpuhp_state_mutex);
 	/*
-	 * If the requested state is CPUHP_AP_ONLINE_DYN, return the
-	 * dynamically allocated state in case of success.
+	 * If the requested state is CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN,
+	 * return the dynamically allocated state in case of success.
 	 */
 	if (!ret && dynstate)
 		return state;