lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <175179607401.406.16648050119866359640.tip-bot2@tip-bot2> Date: Sun, 06 Jul 2025 10:01:14 -0000 From: "tip-bot2 for Rik van Riel" <tip-bot2@...utronix.de> To: linux-tip-commits@...r.kernel.org Cc: Jann Horn <jannh@...gle.com>, Rik van Riel <riel@...riel.com>, Thomas Gleixner <tglx@...utronix.de>, "Yury Norov (NVIDIA)" <yury.norov@...il.com>, x86@...nel.org, linux-kernel@...r.kernel.org Subject: [tip: smp/core] smp: Wait only if work was enqueued The following commit has been merged into the smp/core branch of tip: Commit-ID: 946a7281982530d333eaee62bd1726f25908b3a9 Gitweb: https://git.kernel.org/tip/946a7281982530d333eaee62bd1726f25908b3a9 Author: Rik van Riel <riel@...riel.com> AuthorDate: Wed, 02 Jul 2025 13:52:54 -04:00 Committer: Thomas Gleixner <tglx@...utronix.de> CommitterDate: Sun, 06 Jul 2025 11:57:39 +02:00 smp: Wait only if work was enqueued Whenever work is enqueued for a remote CPU, smp_call_function_many_cond() may need to wait for that work to be completed. However, if no work is enqueued for a remote CPU, because the condition func() evaluated to false for all CPUs, there is no need to wait. Set run_remote only if work was enqueued on remote CPUs. Document the difference between "work enqueued", and "CPU needs to be woken up" Suggested-by: Jann Horn <jannh@...gle.com> Signed-off-by: Rik van Riel <riel@...riel.com> Signed-off-by: Thomas Gleixner <tglx@...utronix.de> Reviewed-by: Yury Norov (NVIDIA) <yury.norov@...il.com> Link: https://lore.kernel.org/all/20250703203019.11331ac3@fangorn --- kernel/smp.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/smp.c b/kernel/smp.c index 99d1fd0..c5e1da7 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -802,7 +802,6 @@ static void smp_call_function_many_cond(const struct cpumask *mask, /* Check if we need remote execution, i.e., any CPU excluding this one. */ if (cpumask_any_and_but(mask, cpu_online_mask, this_cpu) < nr_cpu_ids) { - run_remote = true; cfd = this_cpu_ptr(&cfd_data); cpumask_and(cfd->cpumask, mask, cpu_online_mask); __cpumask_clear_cpu(this_cpu, cfd->cpumask); @@ -816,6 +815,9 @@ static void smp_call_function_many_cond(const struct cpumask *mask, continue; } + /* Work is enqueued on a remote CPU. */ + run_remote = true; + csd_lock(csd); if (wait) csd->node.u_flags |= CSD_TYPE_SYNC; @@ -827,6 +829,10 @@ static void smp_call_function_many_cond(const struct cpumask *mask, #endif trace_csd_queue_cpu(cpu, _RET_IP_, func, csd); + /* + * Kick the remote CPU if this is the first work + * item enqueued. + */ if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) { __cpumask_set_cpu(cpu, cfd->cpumask_ipi); nr_cpus++;
Powered by blists - more mailing lists