From: Indu Bhagat <indu.bhagat@oracle.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Rostedt <rostedt@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
bpf@vger.kernel.org, Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrii Nakryiko <andrii@kernel.org>,
"Jose E. Marchesi" <jemarch@gnu.org>,
Beau Belgrave <beaub@linux.microsoft.com>,
Jens Remus <jremus@linux.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>, Florian Weimer <fweimer@redhat.com>,
Sam James <sam@gentoo.org>
Subject: Re: [PATCH v16 03/10] unwind_user/deferred: Add unwind cache
Date: Wed, 30 Jul 2025 16:58:11 -0700 [thread overview]
Message-ID: <f64326cf-ac2c-4a24-9267-4f2a25045828@oracle.com> (raw)
In-Reply-To: <20250730093249.4833be14@gandalf.local.home>
On 7/30/25 6:32 AM, Steven Rostedt wrote:
> On Tue, 29 Jul 2025 21:55:39 -0700
> Indu Bhagat <indu.bhagat@oracle.com> wrote:
>
>>> diff --git a/include/linux/unwind_deferred.h b/include/linux/unwind_deferred.h
>>> index a5f6e8f8a1a2..baacf4a1eb4c 100644
>>> --- a/include/linux/unwind_deferred.h
>>> +++ b/include/linux/unwind_deferred.h
>>> @@ -12,6 +12,12 @@ void unwind_task_free(struct task_struct *task);
>>>
>>> int unwind_user_faultable(struct unwind_stacktrace *trace);
>>>
>>> +static __always_inline void unwind_reset_info(void)
>>> +{
>>> + if (unlikely(current->unwind_info.cache))
>>> + current->unwind_info.cache->nr_entries = 0;
>>> +}
>>
>> Should the entries[] items upto nr_entries (stack trace info from the
>> previous request) also be reset to 0 here ?
>
> This is in a critical path, there's no reason to reset to zero. The data will
> just be stale. Nothing should care about anything over nr_entries.
>
OK.
Reviewed-By: Indu Bhagat <indu.bhagat@oracle.com>
next prev parent reply other threads:[~2025-07-30 23:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-29 18:23 [PATCH v16 00/10] unwind_user: Deferred unwinding infrastructure Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 01/10] unwind_user: Add user space unwinding API with frame pointer support Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 02/10] unwind_user/deferred: Add unwind_user_faultable() Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 03/10] unwind_user/deferred: Add unwind cache Steven Rostedt
2025-07-30 4:55 ` Indu Bhagat
2025-07-30 13:32 ` Steven Rostedt
2025-07-30 23:58 ` Indu Bhagat [this message]
2025-07-29 18:23 ` [PATCH v16 04/10] unwind_user/deferred: Add deferred unwinding interface Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 05/10] unwind_user/deferred: Make unwind deferral requests NMI-safe Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 06/10] unwind deferred: Use bitmask to determine which callbacks to call Steven Rostedt
2025-09-20 1:00 ` Josh Poimboeuf
2025-09-21 23:47 ` Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 07/10] unwind deferred: Add unwind_completed mask to stop spurious callbacks Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 08/10] unwind: Add USED bit to only have one conditional on way back to user space Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 09/10] unwind deferred: Use SRCU unwind_deferred_task_work() Steven Rostedt
2025-08-01 0:29 ` Paul E. McKenney
2025-08-01 1:11 ` Steven Rostedt
2025-09-20 0:31 ` Josh Poimboeuf
2025-09-21 23:35 ` Steven Rostedt
2025-07-29 18:23 ` [PATCH v16 10/10] unwind: Finish up unwind when a task exits Steven Rostedt
2025-08-02 0:14 ` [PATCH v16 00/10] unwind_user: Deferred unwinding infrastructure patchwork-bot+netdevbpf
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