From: Leo Yan <leo.yan@arm.com>
To: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, suzuki.poulose@arm.com,
mike.leach@arm.com, james.clark@linaro.org,
alexander.shishkin@linux.intel.com, jie.gan@oss.qualcomm.com
Subject: Re: [PATCH v8 08/13] coresight: etm4x: fix inconsistencies with sysfs configuration
Date: Tue, 7 Jul 2026 09:07:03 +0100 [thread overview]
Message-ID: <20260707080703.GC1024232@e132581.arm.com> (raw)
In-Reply-To: <akvyAOJZDqB4yG3m@e129823.arm.com>
On Mon, Jul 06, 2026 at 07:20:48PM +0100, Yeoreum Yun wrote:
[...]
> > However, a corner case was mentioned by Sashiko:
> >
> > | It appears etm4_enable_hw() modifies drvdata->ss_status while executing
> > | via IPI, but sshot_ctrl_store() can modify the same array concurrently
> > | from process context since the lock is no longer held across the
> > | smp_call_function_single() call.
> >
> > "drvdata->ss_status" is a race condition between SMP call and sysfs
> > knobs. Should we change to spinlock_irqsave/irqrestore when access
> > drvdata->ss_status?
>
> I know this, but This is currently ignorable since
> whatever perf or sysfs session, the ss_status is always clear
> the PENDING and STATUS bits (and we make a compromise for this right now).
>
> And the sshot_ctrl_store()'s action is always clear above bits.
>
> So, This is ignorable comment from Sashiko.
I understand it now, we can ignore it. Thanks for explanation.
next prev parent reply other threads:[~2026-07-07 8:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-29 8:59 [PATCH v8 00/13] fix several inconsistencies with sysfs configuration in etmX Yeoreum Yun
2026-06-29 8:59 ` [PATCH v8 01/13] coresight: etm4x: fix wrong check of etm4x_sspcicrn_present() Yeoreum Yun
2026-06-29 8:59 ` [PATCH v8 02/13] coresight: etm4x: fix underflow for usage of (nrseqstate - 1) Yeoreum Yun
2026-06-29 8:59 ` [PATCH v8 03/13] coresight: etm4x: introduce struct etm4_caps Yeoreum Yun
2026-06-29 8:59 ` [PATCH v8 04/13] coresight: etm4x: exclude ss_status from drvdata->config Yeoreum Yun
2026-06-29 8:59 ` [PATCH v8 05/13] coresight: etm4x: remove s_ex_level from config Yeoreum Yun
2026-06-29 8:59 ` [PATCH v8 06/13] coresight: etm4x: remove redundant fields in etmv4_save_state Yeoreum Yun
2026-06-29 9:00 ` [PATCH v8 07/13] coresight: etm4x: fix leaked trace id Yeoreum Yun
2026-06-29 9:00 ` [PATCH v8 08/13] coresight: etm4x: fix inconsistencies with sysfs configuration Yeoreum Yun
2026-07-06 17:21 ` Leo Yan
2026-07-06 18:16 ` Yeoreum Yun
2026-07-07 8:25 ` Leo Yan
2026-07-07 8:59 ` Yeoreum Yun
2026-07-07 9:54 ` Yeoreum Yun
2026-07-06 17:39 ` Leo Yan
2026-07-06 18:20 ` Yeoreum Yun
2026-07-07 8:07 ` Leo Yan [this message]
2026-06-29 9:00 ` [PATCH v8 09/13] coresight: etm4x: missing cscfg_csdev_disable_active_config() in perf enable Yeoreum Yun
2026-06-29 9:00 ` [PATCH v8 10/13] coresight: etm3x: change drvdata->spinlock type to raw_spin_lock_t Yeoreum Yun
2026-06-29 9:00 ` [PATCH v8 11/13] coresight: etm3x: introduce struct etm_caps Yeoreum Yun
2026-06-29 9:00 ` [PATCH v8 12/13] coresight: etm3x: fix inconsistencies with sysfs configuration Yeoreum Yun
2026-06-29 9:00 ` [PATCH v8 13/13] coresight: etm3x: remove redundant cpu online check on etm_enable_sysfs() Yeoreum Yun
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