Hi Maria,
On Tue, Dec 12, 2023 at 10:06 AM Maria Yu <quic_aiquny@xxxxxxxxxxx> wrote:
> Currently pinctrl_select_state is an export symbol and don't have
> effective re-entrance protect design. During async probing of devices
> it's possible to end up in pinctrl_select_state() from multiple
> contexts simultaneously, so make it thread safe.
> More over, when the real racy happened, the system frequently have
> printk message like:
> "not freeing pin xx (xxx) as part of deactivating group xxx - it is
> already used for some other setting".
> Finally the system crashed after the flood log.
> Add per pinctrl lock to ensure the old state and new state transition
> atomization.
> Also move dev error print message outside the region with interrupts
> disabled.
>
> Fixes: 4198a9b57106 ("pinctrl: avoid reload of p state in list iteration")
> Signed-off-by: Maria Yu <quic_aiquny@xxxxxxxxxxx>
Overall this looks good!
> @@ -1262,9 +1263,12 @@ static void pinctrl_link_add(struct pinctrl_dev *pctldev,
> static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
> {
> struct pinctrl_setting *setting, *setting2;
> - struct pinctrl_state *old_state = READ_ONCE(p->state);
> + struct pinctrl_state *old_state;
> int ret;
> + unsigned long flags;
>
> + spin_lock_irqsave(&p->lock, flags);
(...)
> + spin_unlock_irqrestore(&p->lock, flags);
(...)
> + spin_unlock_irqrestore(&p->lock, flags);
Is it possible to use a scoped guard for pinctrl_commit_state()?
#include <linux/cleanup.h>
guard(spinlock_irqsave)(&p->lock);
It saves some code (and no need for flags) and avoid possible
bugs when people add new errorpaths to the code.
Yours,
Linus Walleij
