Hi Guenter,
>> +/*
>> + * applesmc_init_smcreg_try - Try to initialize register cache. Idempotent.
>> + */
>> +static int applesmc_init_smcreg_try(void)
>> +{
>> + struct applesmc_registers *s = &smcreg;
>> + int ret;
>> +
>> + if (s->init_complete)
>> + return 0;
>> +
>> + mutex_init(&s->mutex);
>> +
> I am a bit concerned that mutex_init() can be called multiple times. Are
> you sure this is safe ?
mutex_destroy() is defined as a nop, so I guess the question is whether anything
could be holding the lock when entering a second init. There are no sysfs files
created at that point, so I would say no. The mutex could be put back with a
static initializer, if this is not satisfactory. The real reason to move it to
the smcreg struct was to force a rename of the mutex itself.
>
>> + ret = read_register_count(&s->key_count);
>> + if (ret)
>> + return ret;
>> +
>> + if (!s->cache)
>> + s->cache = kcalloc(s->key_count, sizeof(*s->cache), GFP_KERNEL);
>> + if (!s->cache)
>> + return -ENOMEM;
>> +
>> + s->init_complete = true;
>> +
>> + pr_info("key=%d\n", s->key_count);
>> +
> Hope that means more to macbook users than it does to me ;).
It means a lot from a diagnostic point of view - a normal user does not really
care about the dmesg output anyways. :-)
>> +static int applesmc_init_smcreg(void)
>> +{
>> + int ms, ret;
>> +
>> + for (ms = 0; ms < INIT_TIMEOUT_MSECS; ms += INIT_WAIT_MSECS) {
>> + ret = applesmc_init_smcreg_try();
>> + if (!ret)
>> + return 0;
>> + pr_warn("slow init, retrying\n");
>
> INIT_WAIT_MS is 50ms, so you issue this warning every 50ms for up to
> five seconds. Pretty noisy... sure that is what you want ? Also, does it
> really make sense to retry if the error is ENOMEM ?
With the empirical failure rate, it is extremely unlikely to get more than a
couple of failures in a row - information which in itself could be very useful.
A direct escape on ENOMEM makes sense, though.
Changing the place of the mutex will ripple through all patches, so I will
resend from this one onwards. I suppose you have more comments on the following
patches?
Thanks,
Henrik
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