[patch] x86, bts: fix unlock problem in ds.c

[patch] x86, bts: fix unlock problem in ds.c

[Markus Metzger]

Fix a problem where ds_request() returned an error without releasing the
ds lock.

Reported-by: Stephane Eranian <eranian@gmail.com>
Signed-off-by: Markus Metzger <markus.t.metzger@gmail.com>
---

Index: gits/arch/x86/kernel/ds.c
===================================================================
--- gits.orig/arch/x86/kernel/ds.c	2008-11-15 10:51:51.000000000 +0100
+++ gits/arch/x86/kernel/ds.c	2008-11-15 10:53:43.000000000 +0100
@@ -384,8 +384,9 @@
 
 	spin_lock(&ds_lock);
 
+	error = -EPERM;
 	if (!check_tracer(task))
-		return -EPERM;
+		goto out_unlock;
 
 	error = -ENOMEM;
 	context = ds_alloc_context(task);

Re: [patch] x86, bts: fix unlock problem in ds.c

[Ingo Molnar]

* Markus Metzger <markus.t.metzger@googlemail.com> wrote:

> Fix a problem where ds_request() returned an error without releasing 
> the ds lock.
> 
> Reported-by: Stephane Eranian <eranian@gmail.com>
> Signed-off-by: Markus Metzger <markus.t.metzger@gmail.com>

applied to tip/x86/urgent, thanks Markus!

i also reviewed the other locking branches there and they seem to be 
fine.

	Ingo

Re: [patch] x86, bts: fix unlock problem in ds.c

[stephane eranian]

Markus,

I think this patch is not quite right. You don't want to go out via out_unlock
because you're going to call ds_put_context)() when you did not invoke the
matching ds_get_context() (hidden in ds_alloc_context). It happens later in
the ds_request() function.


On Sat, Nov 15, 2008 at 11:00 AM, Markus Metzger
<markus.t.metzger@googlemail.com> wrote:
> Fix a problem where ds_request() returned an error without releasing the
> ds lock.
>
> Reported-by: Stephane Eranian <eranian@gmail.com>
> Signed-off-by: Markus Metzger <markus.t.metzger@gmail.com>
> ---
>
> Index: gits/arch/x86/kernel/ds.c
> ===================================================================
> --- gits.orig/arch/x86/kernel/ds.c      2008-11-15 10:51:51.000000000 +0100
> +++ gits/arch/x86/kernel/ds.c   2008-11-15 10:53:43.000000000 +0100
> @@ -384,8 +384,9 @@
>
>        spin_lock(&ds_lock);
>
> +       error = -EPERM;
>        if (!check_tracer(task))
> -               return -EPERM;
> +               goto out_unlock;
>
>        error = -ENOMEM;
>        context = ds_alloc_context(task);
>
>
>

Re: [patch] x86, bts: fix unlock problem in ds.c

[Ingo Molnar]

* stephane eranian <eranian@googlemail.com> wrote:

> Markus,
> 
> I think this patch is not quite right. You don't want to go out via 
> out_unlock because you're going to call ds_put_context)() when you 
> did not invoke the matching ds_get_context() (hidden in 
> ds_alloc_context). It happens later in the ds_request() function.

i noticed that, and fixed it via:

 10db4ef: x86, PEBS/DS: fix code flow in ds_request()

can you still see problems with it?

	Ingo

Re: [patch] x86, bts: fix unlock problem in ds.c

[stephane eranian]

On Thu, Nov 20, 2008 at 10:48 PM, Ingo Molnar <mingo@elte.hu> wrote:
>
> * stephane eranian <eranian@googlemail.com> wrote:
>
>> Markus,
>>
>> I think this patch is not quite right. You don't want to go out via
>> out_unlock because you're going to call ds_put_context)() when you
>> did not invoke the matching ds_get_context() (hidden in
>> ds_alloc_context). It happens later in the ds_request() function.
>
> i noticed that, and fixed it via:
>
>  10db4ef: x86, PEBS/DS: fix code flow in ds_request()
>
> can you still see problems with it?
>
Well, I have lots of problems with ds.c so I have heavily modified the
code therefore I have not pulled from
any public tree in several days.