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: <YtXSUuGgjRkjhamA@smile.fi.intel.com> Date: Tue, 19 Jul 2022 00:36:18 +0300 From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> To: Yury Norov <yury.norov@...il.com> Cc: linux-kernel@...r.kernel.org, Alexander Lobakin <alexandr.lobakin@...el.com>, Alexei Starovoitov <ast@...nel.org>, Alexey Klimov <aklimov@...hat.com>, Andrew Morton <akpm@...ux-foundation.org>, Andrii Nakryiko <andrii@...nel.org>, Ben Segall <bsegall@...gle.com>, Christoph Lameter <cl@...ux.com>, Dan Williams <dan.j.williams@...el.com>, Daniel Borkmann <daniel@...earbox.net>, Daniel Bristot de Oliveira <bristot@...hat.com>, Dennis Zhou <dennis@...nel.org>, Dietmar Eggemann <dietmar.eggemann@....com>, Eric Dumazet <edumazet@...gle.com>, Frederic Weisbecker <fweisbec@...il.com>, Guenter Roeck <linux@...ck-us.net>, Ingo Molnar <mingo@...hat.com>, Isabella Basso <isabbasso@...eup.net>, John Fastabend <john.fastabend@...il.com>, Josh Poimboeuf <jpoimboe@...nel.org>, Juergen Gross <jgross@...e.com>, Juri Lelli <juri.lelli@...hat.com>, KP Singh <kpsingh@...nel.org>, Kees Cook <keescook@...omium.org>, Martin KaFai Lau <kafai@...com>, Mel Gorman <mgorman@...e.de>, Miroslav Benes <mbenes@...e.cz>, Nathan Chancellor <nathan@...nel.org>, "Paul E . McKenney" <paulmck@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Randy Dunlap <rdunlap@...radead.org>, Rasmus Villemoes <linux@...musvillemoes.dk>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Song Liu <songliubraving@...com>, Steven Rostedt <rostedt@...dmis.org>, Tejun Heo <tj@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Valentin Schneider <vschneid@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, Vlastimil Babka <vbabka@...e.cz>, Yonghong Song <yhs@...com>, linux-mm@...ck.org, netdev@...r.kernel.org, bpf@...r.kernel.org Subject: Re: [PATCH 07/16] smp: optimize smp_call_function_many_cond() On Mon, Jul 18, 2022 at 12:28:35PM -0700, Yury Norov wrote: > smp_call_function_many_cond() is often passed with cpu_online_mask. > If this is the case, we can use num_online_cpus(), which is O(1) > instead of cpumask_{first,next}(), which is O(N). > > It can be optimized further: if cpu_online_mask has 0 or single bit > set (depending on cpu_online(this_cpu), we can return result without > AND'ing with user's mask. > Caught with CONFIG_DEBUG_BITMAP: > [ 7.830337] Call trace: > [ 7.830397] __bitmap_check_params+0x1d8/0x260 > [ 7.830499] smp_call_function_many_cond+0x1e8/0x45c > [ 7.830607] kick_all_cpus_sync+0x44/0x80 > [ 7.830698] bpf_int_jit_compile+0x34c/0x5cc > [ 7.830796] bpf_prog_select_runtime+0x118/0x190 > [ 7.830900] bpf_prepare_filter+0x3dc/0x51c > [ 7.830995] __get_filter+0xd4/0x170 > [ 7.831145] sk_attach_filter+0x18/0xb0 > [ 7.831236] sock_setsockopt+0x5b0/0x1214 > [ 7.831330] __sys_setsockopt+0x144/0x170 > [ 7.831431] __arm64_sys_setsockopt+0x2c/0x40 > [ 7.831541] invoke_syscall+0x48/0x114 > [ 7.831634] el0_svc_common.constprop.0+0x44/0xfc > [ 7.831745] do_el0_svc+0x30/0xc0 > [ 7.831825] el0_svc+0x2c/0x84 > [ 7.831899] el0t_64_sync_handler+0xbc/0x140 > [ 7.831999] el0t_64_sync+0x18c/0x190 > [ 7.832086] ---[ end trace 0000000000000000 ]--- > [ 7.832375] b1: ffff24d1ffd98a48 > [ 7.832385] b2: ffffa65533a29a38 > [ 7.832393] b3: ffffa65533a29a38 > [ 7.832400] nbits: 256 > [ 7.832407] start: 0 > [ 7.832412] off: 0 > [ 7.832418] smp: Bitmap: parameters check failed > [ 7.832432] smp: include/linux/bitmap.h [363]: bitmap_and Documentation specifically says: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#backtraces-in-commit-mesages ... > + default: > + if (mask == cpu_online_mask) > + return true; Instead, put (missed) break; here and do "default" case together below. > + cpu = cpumask_first_and(mask, cpu_online_mask); > + if (cpu == this_cpu) > + cpu = cpumask_next_and(cpu, mask, cpu_online_mask); > + > + return cpu < nr_cpu_ids; ... > + run_remote = __need_remote_exec(mask, this_cpu); > Now you may remove this blank line. > if (run_remote) { -- With Best Regards, Andy Shevchenko
Powered by blists - more mailing lists