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| author |   Duoming Zhou <duoming@zju.edu.cn> | 2022-04-17 20:03:05 +0800 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-23 10:33:52 +0200 |
| commit | 4d378f2ae58138d4c55684e1d274e7dd94aa6524 (patch) | |
| tree | d9e51f6bf2bd4f39d7c2e060d770d65982bbd008 | |
| parent | usb: dwc3: gadget: Replace list_for_each_entry_safe() if using giveback (diff) | |
| download | linux-dev-4d378f2ae58138d4c55684e1d274e7dd94aa6524.tar.xz linux-dev-4d378f2ae58138d4c55684e1d274e7dd94aa6524.zip | |
drivers: usb: host: Fix deadlock in oxu_bus_suspend()
There is a deadlock in oxu_bus_suspend(), which is shown below:
(Thread 1) | (Thread 2)
| timer_action()
oxu_bus_suspend() | mod_timer()
spin_lock_irq() //(1) | (wait a time)
... | oxu_watchdog()
del_timer_sync() | spin_lock_irq() //(2)
(wait timer to stop) | ...
We hold oxu->lock in position (1) of thread 1, and use
del_timer_sync() to wait timer to stop, but timer handler
also need oxu->lock in position (2) of thread 2. As a result,
oxu_bus_suspend() will block forever.
This patch extracts del_timer_sync() from the protection of
spin_lock_irq(), which could let timer handler to obtain
the needed lock.
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/20220417120305.64577-1-duoming@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/host/oxu210hp-hcd.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/usb/host/oxu210hp-hcd.c b/drivers/usb/host/oxu210hp-hcd.c index ddc155850bfc..8b73c61f86c9 100644 --- a/drivers/usb/host/oxu210hp-hcd.c +++ b/drivers/usb/host/oxu210hp-hcd.c @@ -3909,8 +3909,10 @@ static int oxu_bus_suspend(struct usb_hcd *hcd) } } + spin_unlock_irq(&oxu->lock); /* turn off now-idle HC */ del_timer_sync(&oxu->watchdog); + spin_lock_irq(&oxu->lock); ehci_halt(oxu); hcd->state = HC_STATE_SUSPENDED; |