On Tue, Mar 28, 2023 at 08:34:46AM -0000, tip-bot2 for Paul E. McKenney wrote:
> The following commit has been merged into the smp/core branch of tip:
>
> Commit-ID: 203e435844734cfa503cd1755f35db2514db5cca
> Gitweb: https://git.kernel.org/tip/203e435844734cfa503cd1755f35db2514db5cca
> Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
> AuthorDate: Mon, 20 Mar 2023 17:55:16 -07:00
> Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> CommitterDate: Fri, 24 Mar 2023 11:01:26 +01:00
>
> kernel/smp: Make csdlock_debug= resettable
Very good, thank you! I have removed these from the -rcu tree's "dev"
branch, and if testing goes well will be sending the new version to -next.
Thanx, Paul
> It is currently possible to set the csdlock_debug_enabled static
> branch, but not to reset it. This is an issue when several different
> entities supply kernel boot parameters and also for kernels built with
> CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT=y.
>
> Therefore, make the csdlock_debug=0 kernel boot parameter turn off
> debugging. Last one wins!
>
> Reported-by: Jes Sorensen <Jes.Sorensen@xxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Acked-by: Juergen Gross <jgross@xxxxxxxx>
> Link: https://lore.kernel.org/r/20230321005516.50558-4-paulmck@xxxxxxxxxx
> ---
> Documentation/admin-guide/kernel-parameters.txt | 13 +++++++------
> kernel/smp.c | 11 ++++++++---
> 2 files changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index b15198a..5f2ec4b 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -889,12 +889,13 @@
> cs89x0_media= [HW,NET]
> Format: { rj45 | aui | bnc }
>
> - csdlock_debug= [KNL] Enable debug add-ons of cross-CPU function call
> - handling. When switched on, additional debug data is
> - printed to the console in case a hanging CPU is
> - detected, and that CPU is pinged again in order to try
> - to resolve the hang situation. The default value of
> - this option depends on the CSD_LOCK_WAIT_DEBUG_DEFAULT
> + csdlock_debug= [KNL] Enable or disable debug add-ons of cross-CPU
> + function call handling. When switched on,
> + additional debug data is printed to the console
> + in case a hanging CPU is detected, and that
> + CPU is pinged again in order to try to resolve
> + the hang situation. The default value of this
> + option depends on the CSD_LOCK_WAIT_DEBUG_DEFAULT
> Kconfig option.
>
> dasd= [HW,NET]
> diff --git a/kernel/smp.c b/kernel/smp.c
> index 7a85bcd..298ba75 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -116,11 +116,16 @@ static DEFINE_STATIC_KEY_MAYBE(CONFIG_CSD_LOCK_WAIT_DEBUG_DEFAULT, csdlock_debug
> */
> static int __init csdlock_debug(char *str)
> {
> + int ret;
> unsigned int val = 0;
>
> - get_option(&str, &val);
> - if (val)
> - static_branch_enable(&csdlock_debug_enabled);
> + ret = get_option(&str, &val);
> + if (ret) {
> + if (val)
> + static_branch_enable(&csdlock_debug_enabled);
> + else
> + static_branch_disable(&csdlock_debug_enabled);
> + }
>
> return 1;
> }
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