Hi David,
thanks for your feedback on my first patch, I wasn't aware of checkpatch.pl.
Initially, I had just if-ed the usage of family-data, which did not
look that nice. I was referring to this proof-of-concept workaround in
my initial bug report.
The patch I've submitted is different from my proof-of-concept
workaround. Not unlocking the bus before returning clearly is an
error, I did not extensively test this patch.
> or just increment it while sleeping, which is when it's needed, which
> also looks simpler.
>
> if (external_power) {
> + int refcnt;
> mutex_unlock(&dev->bus_mutex);
>
> + /* prevent the slave from going away */
> + atomic_inc(&sl->refcnt);
> sleep_rem = msleep_interruptible(tm);
> + refcnt = w1_unref_slave(sl);
> - if (sleep_rem != 0)
> + if (sleep_rem != 0 || !refcnt)
> return -EINTR;
>
> i = mutex_lock_interruptible(&dev->bus_mutex);
> if (i != 0)
> return i;
> } else if (!w1_strong_pullup) {
I like this better than my workaround-patch.
One thought occurred to me when looking at this proposal: wouldn't it
be even better to increase sl->refcnt before unlocking the mutex?
I was asking myself if it is possible that the current thread gets
suspended between mutex_unlock(&dev->bus_mutex); and
atomic_inc(&sl->refcnt); thus leaving another thread the change to
unref the device?
(I'm not that familiar with linux scheduling, so my assumption might be void.)
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