From: Steven Rostedt <rostedt@goodmis.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Ian Rogers <irogers@google.com>, Marco Elver <elver@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@kernel.org>,
Will Deacon <will@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
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Subject: Re: [PATCH v3 02/35] compiler-capability-analysis: Add infrastructure for Clang's capability analysis
Date: Thu, 18 Sep 2025 12:14:16 -0400 [thread overview]
Message-ID: <20250918121416.19a8041e@gandalf.local.home> (raw)
In-Reply-To: <1ca90ba0-7bdc-43d1-af12-bba73dd3234a@acm.org>
On Thu, 18 Sep 2025 09:03:17 -0700
Bart Van Assche <bvanassche@acm.org> wrote:
> On 9/18/25 8:58 AM, Ian Rogers wrote:
> > On Thu, Sep 18, 2025 at 7:05 AM Marco Elver <elver@google.com> wrote:
> >> +config WARN_CAPABILITY_ANALYSIS
> >> + bool "Compiler capability-analysis warnings"
> >> + depends on CC_IS_CLANG && CLANG_VERSION >= 220000
> >> + # Branch profiling re-defines "if", which messes with the compiler's
> >> + # ability to analyze __cond_acquires(..), resulting in false positives.
> >> + depends on !TRACE_BRANCH_PROFILING
> >
> > Err, wow! What and huh, and why? Crikes. I'm amazed you found such an
> > option exists. I must be very naive to have never heard of it and now
> > I wonder if it is needed and load bearing?
>
> (+Steven)
>
> This is an old option. I think this commit introduced it:
>
> commit 52f232cb720a7babb752849cbc2cab2d24021209
> Author: Steven Rostedt <rostedt@goodmis.org>
> Date: Wed Nov 12 00:14:40 2008 -0500
>
> tracing: likely/unlikely branch annotation tracer
>
I still use it every year (enable it during December for a few weeks on my
workstation and server) and post the results publicly. When I get time, I
try to fix (add / remove) likely/unlikely statements. Unfortunately, I
haven't had time to look deeper at them.
https://rostedt.org/branches/current/
This year I missed December and ended up running it in January instead.
-- Steve
next prev parent reply other threads:[~2025-09-18 16:13 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-18 13:59 [PATCH v3 00/35] Compiler-Based Capability- and Locking-Analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 01/35] compiler_types: Move lock checking attributes to compiler-capability-analysis.h Marco Elver
2025-09-18 13:59 ` [PATCH v3 02/35] compiler-capability-analysis: Add infrastructure for Clang's capability analysis Marco Elver
2025-09-18 15:58 ` Ian Rogers
2025-09-18 16:03 ` Bart Van Assche
2025-09-18 16:14 ` Steven Rostedt [this message]
2025-09-18 13:59 ` [PATCH v3 03/35] compiler-capability-analysis: Add test stub Marco Elver
2025-09-18 13:59 ` [PATCH v3 04/35] Documentation: Add documentation for Compiler-Based Capability Analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 05/35] checkpatch: Warn about capability_unsafe() without comment Marco Elver
2025-09-18 20:36 ` Joe Perches
2025-09-18 13:59 ` [PATCH v3 06/35] cleanup: Basic compatibility with capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 07/35] lockdep: Annotate lockdep assertions for " Marco Elver
2025-09-18 13:59 ` [PATCH v3 08/35] locking/rwlock, spinlock: Support Clang's " Marco Elver
2025-09-18 13:59 ` [PATCH v3 09/35] compiler-capability-analysis: Change __cond_acquires to take return value Marco Elver
2025-09-18 13:59 ` [PATCH v3 10/35] locking/mutex: Support Clang's capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 11/35] locking/seqlock: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 12/35] bit_spinlock: Include missing <asm/processor.h> Marco Elver
2025-09-18 13:59 ` [PATCH v3 13/35] bit_spinlock: Support Clang's capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 14/35] rcu: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 15/35] srcu: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 16/35] kref: Add capability-analysis annotations Marco Elver
2025-09-18 13:59 ` [PATCH v3 17/35] locking/rwsem: Support Clang's capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 18/35] locking/local_lock: Include missing headers Marco Elver
2025-09-18 13:59 ` [PATCH v3 19/35] locking/local_lock: Support Clang's capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 20/35] locking/ww_mutex: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 21/35] debugfs: Make debugfs_cancellation a capability struct Marco Elver
2025-09-18 13:59 ` [PATCH v3 22/35] compiler-capability-analysis: Remove Sparse support Marco Elver
2025-09-18 13:59 ` [PATCH v3 23/35] compiler-capability-analysis: Remove __cond_lock() function-like helper Marco Elver
2025-09-18 13:59 ` [PATCH v3 24/35] compiler-capability-analysis: Introduce header suppressions Marco Elver
2025-09-18 13:59 ` [PATCH v3 25/35] compiler: Let data_race() imply disabled capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 26/35] MAINTAINERS: Add entry for Capability Analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 27/35] kfence: Enable capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 28/35] kcov: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 29/35] kcsan: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 30/35] stackdepot: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 31/35] rhashtable: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 32/35] printk: Move locking annotation to printk.c Marco Elver
2025-09-18 13:59 ` [PATCH v3 33/35] security/tomoyo: Enable capability analysis Marco Elver
2025-09-18 13:59 ` [PATCH v3 34/35] crypto: " Marco Elver
2025-09-18 13:59 ` [PATCH v3 35/35] sched: Enable capability analysis for core.c and fair.c Marco Elver
2025-09-18 14:15 ` [PATCH v3 00/35] Compiler-Based Capability- and Locking-Analysis Christoph Hellwig
2025-09-18 14:30 ` Marco Elver
2025-09-18 14:38 ` Christoph Hellwig
2025-09-18 17:45 ` Nathan Chancellor
2025-09-18 19:40 ` Nathan Chancellor
2025-09-19 14:08 ` Christoph Hellwig
2025-09-19 14:09 ` Christoph Hellwig
2025-09-22 9:33 ` Marco Elver
2025-09-22 17:11 ` Christoph Hellwig
2025-09-23 19:49 ` Nathan Chancellor
2025-09-19 17:20 ` Bart Van Assche
2025-09-22 17:12 ` Christoph Hellwig
2025-09-20 10:23 ` Marco Elver
2025-09-20 12:44 ` Marco Elver
2025-09-18 15:49 ` Linus Torvalds
2025-09-18 21:26 ` Marco Elver
2025-09-18 21:47 ` Linus Torvalds
2025-09-19 9:10 ` Marco Elver
2025-11-13 14:30 ` Marco Elver
2025-11-14 4:38 ` Nathan Chancellor
2025-11-14 13:22 ` Marco Elver
2025-09-18 16:21 ` Ian Rogers
2025-09-18 19:41 ` [syzbot ci] " syzbot ci
2025-09-19 7:05 ` Marco Elver
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