From: James Clark <james.clark@linaro.org>
To: Leo Yan <leo.yan@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@arm.com>, Suyash Mahar <smahar@meta.com>,
Yeoreum Yun <yeoreum.yun@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Qi Liu <liuqi115@huawei.com>, Junhao He <hejunhao3@huawei.com>,
coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Jonathan Cameron <jic23@kernel.org>,
sashiko-bot <sashiko-bot@kernel.org>
Subject: Re: [PATCH v3 3/8] coresight: etm-perf: Flush workqueue before unloading module
Date: Fri, 14 Aug 2026 09:55:58 +0100 [thread overview]
Message-ID: <df303518-18b8-4068-b6da-774c344aa249@linaro.org> (raw)
In-Reply-To: <20260813141957.GB8904@e132581.arm.com>
On 13/08/2026 15:19, Leo Yan wrote:
> On Tue, Jul 28, 2026 at 04:00:15PM +0100, James Clark wrote:
>> The work queue is never flushed on module unload, so pending work items
>> can run after coresight-config is cleaned up or the .text section is
>> unloaded. The global workqueue also can't be flushed manually, so change
>> it to a local workqueue and flush it on exit.
>
> Why can't we drop the workqueue if it introduces race conditions and
> complexity? In particular, I don't see much benefit from deferring
> the resource release.
>
> According to the comment in __rb_free_aux(), the free_aux() callback
> should never be called from atomic context. It should be safe to release
> the resources directly from the free_aux() callback, without going
> through a workqueue.
>
> Thanks,
> Leo
Nice catch. This was fixed in Perf core in 95ff4ca26c49, very shortly
after the Coresight Perf mode was merged. I'll change this commit to
drop the workqueue completely.
next prev parent reply other threads:[~2026-08-14 8:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-28 15:00 [PATCH v3 0/8] coresight: Prevent per-thread events from sharing a sink James Clark
2026-07-28 15:00 ` [PATCH v3 1/8] coresight: tmc-etr: Don't stop Perf cleanup for active sysfs reads James Clark
2026-08-12 16:45 ` Leo Yan
2026-08-13 9:02 ` James Clark
2026-07-28 15:00 ` [PATCH v3 2/8] coresight: configfs: Don't assume active until cscfg_mgr is set James Clark
2026-08-13 9:09 ` Leo Yan
2026-08-13 9:24 ` James Clark
2026-07-28 15:00 ` [PATCH v3 3/8] coresight: etm-perf: Flush workqueue before unloading module James Clark
2026-08-13 14:19 ` Leo Yan
2026-08-14 8:55 ` James Clark [this message]
2026-07-28 15:00 ` [PATCH v3 4/8] coresight: tmc-etr: Prevent per-thread events from sharing a sink James Clark
2026-08-13 16:05 ` Leo Yan
2026-08-14 9:09 ` James Clark
2026-08-19 8:45 ` Leo Yan
2026-08-20 11:09 ` James Clark
2026-08-20 11:27 ` James Clark
2026-07-28 15:00 ` [PATCH v3 5/8] coresight: tmc-etr: Use session ID for buffer ownership James Clark
2026-07-28 15:00 ` [PATCH v3 6/8] coresight: tmc-etf: Prevent per-thread events from sharing a sink James Clark
2026-07-28 15:00 ` [PATCH v3 7/8] coresight: etb10: " James Clark
2026-07-28 15:00 ` [PATCH v3 8/8] coresight: ultrasoc-smb: " James Clark
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