Hello Nicholas, thank you for your contribution, I really appreciate it !
See inline comments below.
On Sat, Apr 27, 2019 at 12:32 AM Nicholas Mc Guire <hofrat@xxxxxxxxx> wrote:
>
> wait_for_completion_timeout() returns unsigned long (0 on timeout or
> remaining jiffies) not int.
Nice catch !
> thus there is no negative case to check for
> here.
The current code can only break if wait_for_completion_timeout()
returns an unsigned long large enough to make the "int ret" turn
negative. This could result in probe() returning a nonsensical error
value, even though the wait did not time out.
Fortunately that currently cannot happen, because TIMEOUT
(2*HZ) won't overflow an int.
That being said, this return value type mismatch should definitely
be fixed up.
>
> Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
> ---
>
> Problem located with experimental API conformance checking cocci script
>
> Q: It is not really clear if the proposed fix is the right thing here or if
> this should not be using wait_for_completion_interruptible - which would
> return -ERESTARTSYS on interruption. Someone that knows the details of
> this driver would need to check what condition should initiate the
> goto err_reset; which was actually unreachable in the current code.
It's used in probe(), so no need for an interruptible wait, AFAIK.
It can stay as-is.
>
> Patch was compile-tested with. x86_64_defconfig + FIELDBUS_DEV=m,
> HMS_ANYBUSS_BUS=m
> (some unrelated sparse warnings (cast to restricted __be16))
That sounds interesting too. Could you provide more details?
<snip>
> - ret = wait_for_completion_timeout(&cd->card_boot, TIMEOUT);
> - if (ret == 0)
> + time_left = wait_for_completion_timeout(&cd->card_boot, TIMEOUT);
> + if (time_left == 0)
> ret = -ETIMEDOUT;
> - if (ret < 0)
> - goto err_reset;
NAK. This does not jump to err_reset on timeout.
May I suggest the following instead ? (manual formatting)
- ret = wait_for_completion_timeout(&cd->card_boot, TIMEOUT);
- if (ret == 0)
- ret = -ETIMEDOUT;
- if (ret < 0)
- goto err_reset;
+ if (!wait_for_completion_timeout(&cd->card_boot, TIMEOUT)) {
+ ret = -ETIMEDOUT;
+ goto err_reset;
+ }
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