* Why sparse does not support context tracking?
@ 2015-05-04 11:05 Alexander Riesen
2015-05-04 13:38 ` Johannes Berg
0 siblings, 1 reply; 3+ messages in thread
From: Alexander Riesen @ 2015-05-04 11:05 UTC (permalink / raw)
To: linux-sparse, linux-kernel; +Cc: Josh Triplett, Christopher Li, Johannes Berg
Hi,
I tried to instrument my code (a kernel driver) with __must_hold hints
and noticed that they don't really work: a definitely broken code caused
no errors from sparse.
A test in the "sparse" tree confirmed. Here is the test I used:
static int ctx;
static void must_hold(void) __attribute__((context(ctx,1,1)))
{
if (ctx)
;
}
static void bad_must_hold(void)
{
must_hold();
}
After a bit of looking I found a commit which removed context tracking
from the "sparse":
Author: Johannes Berg <johannes@sipsolutions.net> 2008-12-23 10:59:22
Revert the context tracking code
> Do you want to resend your change which revert the context changes?
> Make it base on Josh's git's tree and I will merge your changes in my
> branch.
Below. Or I can give it to you in git if you prefer. I still think we
should redo this in some form so that annotations with different
contexts can work properly, but I don't have time to take care of it
right now.
johannes
>From ca95b62edf1600a2b55ed9ca0515d049807a84fc Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes@sipsolutions.net>
Date: Tue, 23 Dec 2008 10:53:19 +0100
Subject: [PATCH] Revert context tracking code
So it seems that the code has problems with different contexts. Still, it seems
a bit heavy-handed to remove it completely (assuming it worked, of course).
The kernel even has a bit of use for it (not much, admittedly: DRBD and aoe).
Is it be possible to reintroduce the code at least for the same context?
So that it catches at least some locks not taken?
Regards,
Alex Riesen
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Why sparse does not support context tracking?
2015-05-04 11:05 Why sparse does not support context tracking? Alexander Riesen
@ 2015-05-04 13:38 ` Johannes Berg
2015-05-04 14:05 ` Alexander Riesen
0 siblings, 1 reply; 3+ messages in thread
From: Johannes Berg @ 2015-05-04 13:38 UTC (permalink / raw)
To: Alexander Riesen
Cc: linux-sparse, linux-kernel, Josh Triplett, Christopher Li
On Mon, 2015-05-04 at 13:05 +0200, Alexander Riesen wrote:
> Hi,
>
> I tried to instrument my code (a kernel driver) with __must_hold hints
> and noticed that they don't really work: a definitely broken code caused
> no errors from sparse.
> Revert the context tracking code
> So it seems that the code has problems with different contexts. Still, it seems
> a bit heavy-handed to remove it completely (assuming it worked, of course).
It didn't really work. It had a lot of issues that were too big for my
little wireless-focused brain :)
johannes
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Why sparse does not support context tracking?
2015-05-04 13:38 ` Johannes Berg
@ 2015-05-04 14:05 ` Alexander Riesen
0 siblings, 0 replies; 3+ messages in thread
From: Alexander Riesen @ 2015-05-04 14:05 UTC (permalink / raw)
To: Johannes Berg; +Cc: linux-sparse, linux-kernel, Josh Triplett, Christopher Li
On 05/04/2015 03:38 PM, Johannes Berg wrote:
> On Mon, 2015-05-04 at 13:05 +0200, Alexander Riesen wrote:
>>
>> Revert the context tracking code
>>
>> So it seems that the code has problems with different contexts. Still, it seems
>> a bit heavy-handed to remove it completely (assuming it worked, of course).
>
> It didn't really work. It had a lot of issues that were too big for my
> little wireless-focused brain :)
Ah, pity. Wasn't there any hope for it?
^ permalink raw reply [flat|nested] 3+ messages in thread
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