Messages in this thread | | | Date | Wed, 18 Dec 2019 18:28:13 +0100 | From | Dominik Brodowski <> | Subject | Re: [PATCH] mtd: maps: pcmciamtd: fix possible sleep-in-atomic-context bugs in pcmciamtd_set_vpp() |
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On Wed, Dec 18, 2019 at 10:05:52PM +0800, Jia-Ju Bai wrote: > The driver may sleep while holding a spinlock. > The function call path (from bottom to top) in Linux 4.19 is: > > drivers/pcmcia/pcmcia_resource.c, 312: > mutex_lock in pcmcia_fixup_vpp > drivers/mtd/maps/pcmciamtd.c, 309: > pcmcia_fixup_vpp in pcmciamtd_set_vpp > drivers/mtd/maps/pcmciamtd.c, 306: > _raw_spin_lock_irqsave in pcmciamtd_set_vpp > > drivers/pcmcia/pcmcia_resource.c, 312: > mutex_lock in pcmcia_fixup_vpp > drivers/mtd/maps/pcmciamtd.c, 312: > pcmcia_fixup_vpp in pcmciamtd_set_vpp > drivers/mtd/maps/pcmciamtd.c, 306: > _raw_spin_lock_irqsave in pcmciamtd_set_vp > > mutex_lock() may sleep at runtime.
Thanks for noticing this issue.
> To fix these bugs, pcmcia_fixup_vpp() is called without holding the > spinlock.
I don't think that this is the right approach here -- we lose the protection against races in calls to pcmcia_fixup_vpp(). Instead, we should change the spinlock to a mutex, which seems to be sufficient here. Could you prepare such a patch, please?
Thanks, Dominik
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