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Subject[tip: sched/core] livepatch: Skip task_call_func() for current task
The following commit has been merged into the sched/core branch of tip:

Commit-ID: 383439d3d400d4c5a7ffb4495124adc6be6a05e2
Gitweb: https://git.kernel.org/tip/383439d3d400d4c5a7ffb4495124adc6be6a05e2
Author: Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate: Fri, 24 Feb 2023 08:49:59 -08:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 22 Mar 2023 17:09:28 +01:00

livepatch: Skip task_call_func() for current task

The current task doesn't need the scheduler's protection to unwind its
own stack.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Link: https://lore.kernel.org/r/4b92e793462d532a05f03767151fa29db3e68e13.1677257135.git.jpoimboe@kernel.org
---
kernel/livepatch/transition.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 135fc73..824e2e3 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -312,7 +312,11 @@ static bool klp_try_switch_task(struct task_struct *task)
* functions. If all goes well, switch the task to the target patch
* state.
*/
- ret = task_call_func(task, klp_check_and_switch_task, &old_name);
+ if (task == current)
+ ret = klp_check_and_switch_task(current, &old_name);
+ else
+ ret = task_call_func(task, klp_check_and_switch_task, &old_name);
+
switch (ret) {
case 0: /* success */
break;
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