From: Dominik Brodowski <linux@dominikbrodowski.net>
To: Maxwell Doose <m32285159@gmail.com>
Cc: open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] pcmcia: cs: Replace manual mutex locking with guard(mutex)
Date: Thu, 4 Jun 2026 08:05:44 +0200 [thread overview]
Message-ID: <aiEVuL3fWF-93hHS@shine.dominikbrodowski.net> (raw)
In-Reply-To: <20260603062714.45848-1-m32285159@gmail.com>
Am Wed, Jun 03, 2026 at 01:27:12AM -0500 schrieb Maxwell Doose:
> The current code uses manual mutex locking. Replace it with the RAII
> guard(mutex) alongside some helpers to help condense some sections and
> increase readability.
As the PCMCIA subsystem is in "odd fixes" mode, I don't see real advantages
for this patch.
Thanks,
Dominik
> Signed-off-by: Maxwell Doose <m32285159@gmail.com>
> ---
> drivers/pcmcia/cs.c | 208 ++++++++++++++++++++++----------------------
> 1 file changed, 104 insertions(+), 104 deletions(-)
>
> diff --git a/drivers/pcmcia/cs.c b/drivers/pcmcia/cs.c
> index adbc486af2ea..200167eb863f 100644
> --- a/drivers/pcmcia/cs.c
> +++ b/drivers/pcmcia/cs.c
> @@ -159,9 +159,8 @@ int pcmcia_register_socket(struct pcmcia_socket *socket)
> spin_lock_init(&socket->thread_lock);
>
> if (socket->resource_ops->init) {
> - mutex_lock(&socket->ops_mutex);
> - ret = socket->resource_ops->init(socket);
> - mutex_unlock(&socket->ops_mutex);
> + scoped_guard(mutex, &socket->ops_mutex)
> + ret = socket->resource_ops->init(socket);
> if (ret)
> goto err;
> }
> @@ -220,9 +219,9 @@ void pcmcia_unregister_socket(struct pcmcia_socket *socket)
>
> /* wait for sysfs to drop all references */
> if (socket->resource_ops->exit) {
> - mutex_lock(&socket->ops_mutex);
> + guard(mutex)(&socket->ops_mutex);
> +
> socket->resource_ops->exit(socket);
> - mutex_unlock(&socket->ops_mutex);
> }
> wait_for_completion(&socket->socket_released);
> } /* pcmcia_unregister_socket */
> @@ -259,6 +258,24 @@ static int socket_reset(struct pcmcia_socket *skt)
> return -ETIMEDOUT;
> }
>
> +static void socket_shutdown_helper(struct pcmcia_socket *s)
> +{
> + guard(mutex)(&s->ops_mutex);
> +
> + s->state &= SOCKET_INUSE | SOCKET_PRESENT;
> + msleep(shutdown_delay * 10);
> + s->state &= SOCKET_INUSE;
> +
> + /* Blank out the socket state */
> + s->socket = dead_socket;
> + s->ops->init(s);
> + s->ops->set_socket(s, &s->socket);
> + s->lock_count = 0;
> + kfree(s->fake_cis);
> + s->fake_cis = NULL;
> + s->functions = 0;
> +}
> +
> /*
> * socket_setup() and socket_shutdown() are called by the main event handler
> * when card insertion and removal events are received.
> @@ -274,27 +291,13 @@ static void socket_shutdown(struct pcmcia_socket *s)
> if (s->callback)
> s->callback->remove(s);
>
> - mutex_lock(&s->ops_mutex);
> - s->state &= SOCKET_INUSE | SOCKET_PRESENT;
> - msleep(shutdown_delay * 10);
> - s->state &= SOCKET_INUSE;
> -
> - /* Blank out the socket state */
> - s->socket = dead_socket;
> - s->ops->init(s);
> - s->ops->set_socket(s, &s->socket);
> - s->lock_count = 0;
> - kfree(s->fake_cis);
> - s->fake_cis = NULL;
> - s->functions = 0;
> -
> /* From here on we can be sure that only we (that is, the
> * pccardd thread) accesses this socket, and all (16-bit)
> * PCMCIA interactions are gone. Therefore, release
> * ops_mutex so that we don't get a sysfs-related lockdep
> * warning.
> */
> - mutex_unlock(&s->ops_mutex);
> + socket_shutdown_helper(s);
>
> #ifdef CONFIG_CARDBUS
> cb_free(s);
> @@ -396,6 +399,10 @@ static int socket_insert(struct pcmcia_socket *skt)
>
> dev_dbg(&skt->dev, "insert\n");
>
> + /*
> + * NOTE: Converting to guard(mutex) may require refactoring some of this
> + * code so not converted.
> + */
> mutex_lock(&skt->ops_mutex);
> if (skt->state & SOCKET_INUSE) {
> mutex_unlock(&skt->ops_mutex);
> @@ -435,7 +442,7 @@ static int socket_suspend(struct pcmcia_socket *skt)
> if ((skt->state & SOCKET_SUSPEND) && !(skt->state & SOCKET_IN_RESUME))
> return -EBUSY;
>
> - mutex_lock(&skt->ops_mutex);
> + guard(mutex)(&skt->ops_mutex);
> /* store state on first suspend, but not after spurious wakeups */
> if (!(skt->state & SOCKET_IN_RESUME))
> skt->suspended_state = skt->state;
> @@ -446,20 +453,21 @@ static int socket_suspend(struct pcmcia_socket *skt)
> skt->ops->suspend(skt);
> skt->state |= SOCKET_SUSPEND;
> skt->state &= ~SOCKET_IN_RESUME;
> - mutex_unlock(&skt->ops_mutex);
> +
> return 0;
> }
>
> static int socket_early_resume(struct pcmcia_socket *skt)
> {
> - mutex_lock(&skt->ops_mutex);
> + guard(mutex)(&skt->ops_mutex);
> +
> skt->socket = dead_socket;
> skt->ops->init(skt);
> skt->ops->set_socket(skt, &skt->socket);
> if (skt->state & SOCKET_PRESENT)
> skt->resume_status = socket_setup(skt, resume_delay);
> skt->state |= SOCKET_IN_RESUME;
> - mutex_unlock(&skt->ops_mutex);
> +
> return 0;
> }
>
> @@ -467,9 +475,8 @@ static int socket_late_resume(struct pcmcia_socket *skt)
> {
> int ret = 0;
>
> - mutex_lock(&skt->ops_mutex);
> - skt->state &= ~(SOCKET_SUSPEND | SOCKET_IN_RESUME);
> - mutex_unlock(&skt->ops_mutex);
> + scoped_guard(mutex, &skt->ops_mutex)
> + skt->state &= ~(SOCKET_SUSPEND | SOCKET_IN_RESUME);
>
> if (!(skt->state & SOCKET_PRESENT)) {
> ret = socket_insert(skt);
> @@ -572,6 +579,48 @@ static void socket_detect_change(struct pcmcia_socket *skt)
> }
> }
>
> +static int pccardd_helper(struct pcmcia_socket *skt, unsigned int events,
> + unsigned int sysfs_events)
> +{
> + int ret;
> +
> + guard(mutex)(&skt->skt_mutex);
> +
> + if (events & SS_DETECT)
> + socket_detect_change(skt);
> +
> + if (sysfs_events) {
> + if (sysfs_events & PCMCIA_UEVENT_EJECT)
> + socket_remove(skt);
> + if (sysfs_events & PCMCIA_UEVENT_INSERT)
> + socket_insert(skt);
> + if ((sysfs_events & PCMCIA_UEVENT_SUSPEND) &&
> + !(skt->state & SOCKET_CARDBUS)) {
> + if (skt->callback)
> + ret = skt->callback->suspend(skt);
> + else
> + ret = 0;
> + if (!ret) {
> + socket_suspend(skt);
> + msleep(100);
> + }
> + }
> + if ((sysfs_events & PCMCIA_UEVENT_RESUME) &&
> + !(skt->state & SOCKET_CARDBUS)) {
> + ret = socket_resume(skt);
> + if (!ret && skt->callback)
> + skt->callback->resume(skt);
> + }
> + if ((sysfs_events & PCMCIA_UEVENT_REQUERY) &&
> + !(skt->state & SOCKET_CARDBUS)) {
> + if (!ret && skt->callback)
> + skt->callback->requery(skt);
> + }
> + }
> +
> + return ret;
> +}
> +
> static int pccardd(void *__skt)
> {
> struct pcmcia_socket *skt = __skt;
> @@ -613,39 +662,7 @@ static int pccardd(void *__skt)
> skt->sysfs_events = 0;
> spin_unlock_irqrestore(&skt->thread_lock, flags);
>
> - mutex_lock(&skt->skt_mutex);
> - if (events & SS_DETECT)
> - socket_detect_change(skt);
> -
> - if (sysfs_events) {
> - if (sysfs_events & PCMCIA_UEVENT_EJECT)
> - socket_remove(skt);
> - if (sysfs_events & PCMCIA_UEVENT_INSERT)
> - socket_insert(skt);
> - if ((sysfs_events & PCMCIA_UEVENT_SUSPEND) &&
> - !(skt->state & SOCKET_CARDBUS)) {
> - if (skt->callback)
> - ret = skt->callback->suspend(skt);
> - else
> - ret = 0;
> - if (!ret) {
> - socket_suspend(skt);
> - msleep(100);
> - }
> - }
> - if ((sysfs_events & PCMCIA_UEVENT_RESUME) &&
> - !(skt->state & SOCKET_CARDBUS)) {
> - ret = socket_resume(skt);
> - if (!ret && skt->callback)
> - skt->callback->resume(skt);
> - }
> - if ((sysfs_events & PCMCIA_UEVENT_REQUERY) &&
> - !(skt->state & SOCKET_CARDBUS)) {
> - if (!ret && skt->callback)
> - skt->callback->requery(skt);
> - }
> - }
> - mutex_unlock(&skt->skt_mutex);
> + ret = pccardd_helper(skt, events, sysfs_events);
>
> if (events || sysfs_events)
> continue;
> @@ -663,9 +680,9 @@ static int pccardd(void *__skt)
>
> /* shut down socket, if a device is still present */
> if (skt->state & SOCKET_PRESENT) {
> - mutex_lock(&skt->skt_mutex);
> + guard(mutex)(&skt->skt_mutex);
> +
> socket_remove(skt);
> - mutex_unlock(&skt->skt_mutex);
> }
>
> /* remove from the device core */
> @@ -722,17 +739,13 @@ EXPORT_SYMBOL(pcmcia_parse_uevents);
> /* register pcmcia_callback */
> int pccard_register_pcmcia(struct pcmcia_socket *s, struct pcmcia_callback *c)
> {
> - int ret = 0;
> -
> /* s->skt_mutex also protects s->callback */
> - mutex_lock(&s->skt_mutex);
> + guard(mutex)(&s->skt_mutex);
>
> if (c) {
> /* registration */
> - if (s->callback) {
> - ret = -EBUSY;
> - goto err;
> - }
> + if (s->callback)
> + return -EBUSY;
>
> s->callback = c;
>
> @@ -740,10 +753,8 @@ int pccard_register_pcmcia(struct pcmcia_socket *s, struct pcmcia_callback *c)
> s->callback->add(s);
> } else
> s->callback = NULL;
> - err:
> - mutex_unlock(&s->skt_mutex);
>
> - return ret;
> + return 0;
> }
> EXPORT_SYMBOL(pccard_register_pcmcia);
>
> @@ -759,35 +770,27 @@ int pcmcia_reset_card(struct pcmcia_socket *skt)
>
> dev_dbg(&skt->dev, "resetting socket\n");
>
> - mutex_lock(&skt->skt_mutex);
> - do {
> - if (!(skt->state & SOCKET_PRESENT)) {
> - dev_dbg(&skt->dev, "can't reset, not present\n");
> - ret = -ENODEV;
> - break;
> - }
> - if (skt->state & SOCKET_SUSPEND) {
> - dev_dbg(&skt->dev, "can't reset, suspended\n");
> - ret = -EBUSY;
> - break;
> - }
> - if (skt->state & SOCKET_CARDBUS) {
> - dev_dbg(&skt->dev, "can't reset, is cardbus\n");
> - ret = -EPERM;
> - break;
> - }
> + guard(mutex)(&skt->skt_mutex);
>
> - if (skt->callback)
> - skt->callback->suspend(skt);
> - mutex_lock(&skt->ops_mutex);
> + if (!(skt->state & SOCKET_PRESENT)) {
> + dev_dbg(&skt->dev, "can't reset, not present\n");
> + return -ENODEV;
> + }
> + if (skt->state & SOCKET_SUSPEND) {
> + dev_dbg(&skt->dev, "can't reset, suspended\n");
> + return -EBUSY;
> + }
> + if (skt->state & SOCKET_CARDBUS) {
> + dev_dbg(&skt->dev, "can't reset, is cardbus\n");
> + return -EPERM;
> + }
> +
> + if (skt->callback)
> + skt->callback->suspend(skt);
> + scoped_guard(mutex, &skt->ops_mutex)
> ret = socket_reset(skt);
> - mutex_unlock(&skt->ops_mutex);
> - if ((ret == 0) && (skt->callback))
> - skt->callback->resume(skt);
> -
> - ret = 0;
> - } while (0);
> - mutex_unlock(&skt->skt_mutex);
> + if ((ret == 0) && (skt->callback))
> + skt->callback->resume(skt);
>
> return ret;
> } /* reset_card */
> @@ -820,13 +823,10 @@ static int __pcmcia_pm_op(struct device *dev,
> int (*callback) (struct pcmcia_socket *skt))
> {
> struct pcmcia_socket *s = container_of(dev, struct pcmcia_socket, dev);
> - int ret;
>
> - mutex_lock(&s->skt_mutex);
> - ret = callback(s);
> - mutex_unlock(&s->skt_mutex);
> + guard(mutex)(&s->skt_mutex);
>
> - return ret;
> + return callback(s);
> }
>
> static int pcmcia_socket_dev_suspend_noirq(struct device *dev)
> --
> 2.54.0
>
>
next prev parent reply other threads:[~2026-06-04 6:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-03 6:27 Maxwell Doose
2026-06-03 17:44 ` kernel test robot
2026-06-04 6:05 ` Dominik Brodowski [this message]
2026-06-04 13:26 ` Maxwell Doose
2026-06-04 13:40 ` Dominik Brodowski
2026-06-04 14:21 ` Maxwell Doose
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