From: Leo Yan <leo.yan@arm.com>
To: James Clark <james.clark@linaro.org>
Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Mao Jinlong <quic_jinlmao@quicinc.com>
Subject: Re: [PATCH v3 8/8] coresight: Unify error handling in coresight_register()
Date: Mon, 9 Feb 2026 11:28:19 +0000 [thread overview]
Message-ID: <20260209112819.GL3529712@e132581.arm.com> (raw)
In-Reply-To: <e451547b-15a7-4296-a5da-379640c141c7@linaro.org>
On Tue, Feb 03, 2026 at 11:15:55AM +0000, James Clark wrote:
[...]
> > diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> > index 955af43010446803030973c72f07315492b2fcf3..65cf975493c86de42515845147d90497aa20c595 100644
> > --- a/drivers/hwtracing/coresight/coresight-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-core.c
> > @@ -1326,7 +1326,6 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
> > {
> > int ret;
> > struct coresight_device *csdev;
> > - bool registered = false;
> > csdev = kzalloc(sizeof(*csdev), GFP_KERNEL);
> > if (!csdev) {
> > @@ -1380,7 +1379,8 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
> > * All resources are free'd explicitly via
> > * coresight_device_release(), triggered from put_device().
> > */
> > - goto out_unlock;
> > + mutex_unlock(&coresight_mutex);
> > + goto err_out;
>
> I'm not sure if replacing the "registered" system with extra calls to unlock
> is necessarily better. I think the whole point of out_unlock was to have a
> single call to unlock so it couldn't be forgotten or didn't need to be
> duplicated.
The motivation for this patch is to use out_unlock as a central point
for releasing resources via coresight_unregister().
The tricky case is a device_register() failure. Since the device is not
successfully registered, there is no need to call coresight_unregister()
to release bus resources. However, the mutex and platform data still
need to be released. The code here unlocks and jumps to err_out to
release the platform data.
> Probably a better way to clean this up would be to pull out a function for
> all the stuff that needs to be locked and use guard(). Then do the stuff
> that doesn't need to be locked after that function. Either way it doesn't
> look wrong.
If so, although locking is not a concern, the device_register() failures
still need to release platform data particularly. That means we still
need extra flag (or returned error) to indicate if it is a
device_register() failure.
I understand we don't want multiple places for mutex release. It is
not bad to keep the "registered" flag and drop this patch.
Thanks,
Leo
next prev parent reply other threads:[~2026-02-09 11:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-02 9:33 [PATCH v3 0/8] coresight: Fix device registration and unregistration Leo Yan
2026-02-02 9:33 ` [PATCH v3 1/8] coresight: Fix memory leak in coresight_alloc_device_name() Leo Yan
2026-02-02 9:33 ` [PATCH v3 2/8] coresight: Get parent device reference after sink ID map allocation Leo Yan
2026-02-02 9:33 ` [PATCH v3 3/8] coresight: Protect unregistration with mutex Leo Yan
2026-02-02 9:34 ` [PATCH v3 4/8] coresight: Refactor output connection sysfs link cleanup Leo Yan
2026-02-02 9:34 ` [PATCH v3 5/8] coresight: Refactor sysfs connection group cleanup Leo Yan
2026-02-02 9:34 ` [PATCH v3 6/8] coresight: Move sink validation into etm_perf_add_symlink_sink() Leo Yan
2026-02-02 9:34 ` [PATCH v3 7/8] coresight: Do not mix success path with failure handling Leo Yan
2026-02-02 9:34 ` [PATCH v3 8/8] coresight: Unify error handling in coresight_register() Leo Yan
2026-02-03 11:15 ` James Clark
2026-02-09 11:28 ` Leo Yan [this message]
2026-02-09 11:59 ` Leo Yan
2026-02-03 11:13 ` [PATCH v3 0/8] coresight: Fix device registration and unregistration James Clark
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