| Message ID | 20220715072951.859586-1-dario.binacchi@amarulasolutions.com |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v3] can: slcan: do not sleep with a spin lock held | expand |
On Fri, Jul 15, 2022 at 1:00 PM Dario Binacchi <dario.binacchi@amarulasolutions.com> wrote: > > We can't call close_candev() with a spin lock held, so release the lock > before calling it. After calling close_candev(), we can update the > fields of the private `struct can_priv' without having to acquire the > lock. But here we are updating private 'struct can_priv' before close_candev() while taking the lock. If we go by change logs, then spin_unlock_bh() need to called before close_candev() and we can update the private 'struct can_priv' in existing place. > > Fixes: c4e54b063f42f ("can: slcan: use CAN network device driver API") > Reported-by: kernel test robot <oliver.sang@intel.com> > Link: https://lore.kernel.org/linux-kernel/Ysrf1Yc5DaRGN1WE@xsang-OptiPlex-9020/ > Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com> > > --- > > Changes in v3: > - Update the commit message. > - Reset sl->rcount and sl->xleft before releasing the spin lock. > > Changes in v2: > - Release the lock just before calling the close_candev(). > > drivers/net/can/slcan/slcan-core.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c > index 54d29a410ad5..d40ddc596596 100644 > --- a/drivers/net/can/slcan/slcan-core.c > +++ b/drivers/net/can/slcan/slcan-core.c > @@ -689,15 +689,14 @@ static int slc_close(struct net_device *dev) > clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); > } > netif_stop_queue(dev); > + sl->rcount = 0; > + sl->xleft = 0; > + spin_unlock_bh(&sl->lock); > close_candev(dev); > sl->can.state = CAN_STATE_STOPPED; > if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN) > sl->can.bittiming.bitrate = CAN_BITRATE_UNSET; > > - sl->rcount = 0; > - sl->xleft = 0; > - spin_unlock_bh(&sl->lock); > - > return 0; > } > > -- > 2.32.0 > >
Hello Souptick, On Thu, Jul 21, 2022 at 3:58 AM Souptick Joarder <jrdr.linux@gmail.com> wrote: > > On Fri, Jul 15, 2022 at 1:00 PM Dario Binacchi > <dario.binacchi@amarulasolutions.com> wrote: > > > > We can't call close_candev() with a spin lock held, so release the lock > > before calling it. After calling close_candev(), we can update the > > fields of the private `struct can_priv' without having to acquire the > > lock. > > But here we are updating private 'struct can_priv' before close_candev() while > taking the lock. If we go by change logs, then spin_unlock_bh() need to called > before close_candev() and we can update the private 'struct can_priv' > in existing place. sl-> rcount and sl-> xleft are not part of 'struct can_priv' and can be reset after calling netif_stop_queu() because it inhibits any serial reception/transmission. Thanks and regards, Dario > > > > > Fixes: c4e54b063f42f ("can: slcan: use CAN network device driver API") > > Reported-by: kernel test robot <oliver.sang@intel.com> > > Link: https://lore.kernel.org/linux-kernel/Ysrf1Yc5DaRGN1WE@xsang-OptiPlex-9020/ > > Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com> > > > > --- > > > > Changes in v3: > > - Update the commit message. > > - Reset sl->rcount and sl->xleft before releasing the spin lock. > > > > Changes in v2: > > - Release the lock just before calling the close_candev(). > > > > drivers/net/can/slcan/slcan-core.c | 7 +++---- > > 1 file changed, 3 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c > > index 54d29a410ad5..d40ddc596596 100644 > > --- a/drivers/net/can/slcan/slcan-core.c > > +++ b/drivers/net/can/slcan/slcan-core.c > > @@ -689,15 +689,14 @@ static int slc_close(struct net_device *dev) > > clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); > > } > > netif_stop_queue(dev); > > + sl->rcount = 0; > > + sl->xleft = 0; > > + spin_unlock_bh(&sl->lock); > > close_candev(dev); > > sl->can.state = CAN_STATE_STOPPED; > > if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN) > > sl->can.bittiming.bitrate = CAN_BITRATE_UNSET; > > > > - sl->rcount = 0; > > - sl->xleft = 0; > > - spin_unlock_bh(&sl->lock); > > - > > return 0; > > } > > > > -- > > 2.32.0 > > > >
diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c index 54d29a410ad5..d40ddc596596 100644 --- a/drivers/net/can/slcan/slcan-core.c +++ b/drivers/net/can/slcan/slcan-core.c @@ -689,15 +689,14 @@ static int slc_close(struct net_device *dev) clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); } netif_stop_queue(dev); + sl->rcount = 0; + sl->xleft = 0; + spin_unlock_bh(&sl->lock); close_candev(dev); sl->can.state = CAN_STATE_STOPPED; if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN) sl->can.bittiming.bitrate = CAN_BITRATE_UNSET; - sl->rcount = 0; - sl->xleft = 0; - spin_unlock_bh(&sl->lock); - return 0; }
We can't call close_candev() with a spin lock held, so release the lock before calling it. After calling close_candev(), we can update the fields of the private `struct can_priv' without having to acquire the lock. Fixes: c4e54b063f42f ("can: slcan: use CAN network device driver API") Reported-by: kernel test robot <oliver.sang@intel.com> Link: https://lore.kernel.org/linux-kernel/Ysrf1Yc5DaRGN1WE@xsang-OptiPlex-9020/ Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com> --- Changes in v3: - Update the commit message. - Reset sl->rcount and sl->xleft before releasing the spin lock. Changes in v2: - Release the lock just before calling the close_candev(). drivers/net/can/slcan/slcan-core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)