* [PATCH] parisc: Drop out of get_whan() if task is running again
@ 2020-12-17 16:57 Helge Deller
2020-12-17 18:04 ` John David Anglin
0 siblings, 1 reply; 3+ messages in thread
From: Helge Deller @ 2020-12-17 16:57 UTC (permalink / raw)
To: linux-parisc, James Bottomley, John David Anglin
Signed-off-by: Helge Deller <deller@gmx.de>
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index a92a23d6acd9..fda1c1a6a444 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -260,6 +260,8 @@ get_wchan(struct task_struct *p)
do {
if (unwind_once(&info) < 0)
return 0;
+ if (p->state == TASK_RUNNING)
+ return 0;
ip = info.ip;
if (!in_sched_functions(ip))
return ip;
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] parisc: Drop out of get_whan() if task is running again
2020-12-17 16:57 [PATCH] parisc: Drop out of get_whan() if task is running again Helge Deller
@ 2020-12-17 18:04 ` John David Anglin
2020-12-17 18:06 ` Helge Deller
0 siblings, 1 reply; 3+ messages in thread
From: John David Anglin @ 2020-12-17 18:04 UTC (permalink / raw)
To: Helge Deller, linux-parisc, James Bottomley
This seems to be a hack to work around a race in p->state. Don't see this check in other implementations.
On 2020-12-17 11:57 a.m., Helge Deller wrote:
> Signed-off-by: Helge Deller <deller@gmx.de>
>
> diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
> index a92a23d6acd9..fda1c1a6a444 100644
> --- a/arch/parisc/kernel/process.c
> +++ b/arch/parisc/kernel/process.c
> @@ -260,6 +260,8 @@ get_wchan(struct task_struct *p)
> do {
> if (unwind_once(&info) < 0)
> return 0;
> + if (p->state == TASK_RUNNING)
> + return 0;
> ip = info.ip;
> if (!in_sched_functions(ip))
> return ip;
Dave
--
John David Anglin dave.anglin@bell.net
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] parisc: Drop out of get_whan() if task is running again
2020-12-17 18:04 ` John David Anglin
@ 2020-12-17 18:06 ` Helge Deller
0 siblings, 0 replies; 3+ messages in thread
From: Helge Deller @ 2020-12-17 18:06 UTC (permalink / raw)
To: John David Anglin, linux-parisc, James Bottomley
On 12/17/20 7:04 PM, John David Anglin wrote:
> This seems to be a hack to work around a race in p->state. Don't see this check in other implementations.
In arch/x86/kernel/process.c:
} while (count++ < 16 && p->state != TASK_RUNNING);
But I think we should implement CONFIG_THREAD_INFO_IN_TASK
and thus try_get_task_stack() too..
Helge
>
> On 2020-12-17 11:57 a.m., Helge Deller wrote:
>> Signed-off-by: Helge Deller <deller@gmx.de>
>>
>> diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
>> index a92a23d6acd9..fda1c1a6a444 100644
>> --- a/arch/parisc/kernel/process.c
>> +++ b/arch/parisc/kernel/process.c
>> @@ -260,6 +260,8 @@ get_wchan(struct task_struct *p)
>> do {
>> if (unwind_once(&info) < 0)
>> return 0;
>> + if (p->state == TASK_RUNNING)
>> + return 0;
>> ip = info.ip;
>> if (!in_sched_functions(ip))
>> return ip;
>
> Dave
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-12-17 18:08 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2020-12-17 16:57 [PATCH] parisc: Drop out of get_whan() if task is running again Helge Deller
2020-12-17 18:04 ` John David Anglin
2020-12-17 18:06 ` Helge Deller
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