Messages in this thread | | | Subject | Re: [PATCH v11 04/14] s390/zcrypt: driver callback to indicate resource in use | From | Tony Krowiak <> | Date | Mon, 16 Nov 2020 11:23:38 -0500 |
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On 11/13/20 7:00 PM, Halil Pasic wrote: > On Fri, 13 Nov 2020 16:30:31 -0500 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >> We will be using the mutex_trylock() function in our sysfs >> assignment >> interfaces which make the call to the AP bus to check permissions (which >> also >> locks ap_perms). If the mutex_trylock() fails, we return from the assignment >> function with -EBUSY. This should resolve that potential deadlock issue. > It resolves the deadlock issue only if in_use() is also doing > mutex_trylock(), but the if in_use doesn't take the lock it > needs to back off (and so does it's client code) i.e. a boolean as > return value won't do.
Makes sense. I'll change the in_use callback to return an int and use mutex_trylock() for the vfio_ap_mdev_in_use() function. If the lock can not be obtained, the function will return -EBUSY.
> > Regards, > Halil
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