[Qemu-devel] [PATCH] linux-user/main.c: Remove redundant end_exclusive()

[Qemu-devel] [PATCH] linux-user/main.c: Remove redundant end_exclusive()

[Chen Gang S]

start/end_exclusive() need be pairs, except the start_exclusive() in
stop_all_tasks() which is only used by force_sig(), which will be abort.
So at present, start_exclusive() in stop_all_task() need not be paired.

So need remove end_exclusive() after queue_signal(). If could really
return from queue_signal(), which meant stop_all_task() is not called (
at least, not called in time), the next end_exclusive() would be issue.

Also use TARGET_SIGSEGV instead of SIGSEGV, since queue_signal() is for
TARGET_*, at present, queue_signal() is a normal function which may call
force_sig(), or return (may kill pid or queue signal, then return).

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
 linux-user/main.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index 8c70be4..a410a17 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -517,14 +517,12 @@ segv:
     end_exclusive();
     /* We get the PC of the entry address - which is as good as anything,
        on a real kernel what you get depends on which mode it uses. */
-    info.si_signo = SIGSEGV;
+    info.si_signo = TARGET_SIGSEGV;
     info.si_errno = 0;
     /* XXX: check env->error_code */
     info.si_code = TARGET_SEGV_MAPERR;
     info._sifields._sigfault._addr = env->exception.vaddress;
     queue_signal(env, info.si_signo, &info);
-
-    end_exclusive();
 }
 
 /* Handle a jump to the kernel code page.  */
-- 
1.9.3 (Apple Git-50)

Re: [Qemu-devel] [PATCH] linux-user/main.c: Remove redundant end_exclusive()

[Peter Maydell]

On 23 January 2015 at 10:17, Chen Gang S <gang.chen@sunrus.com.cn> wrote:
> start/end_exclusive() need be pairs, except the start_exclusive() in
> stop_all_tasks() which is only used by force_sig(), which will be abort.
> So at present, start_exclusive() in stop_all_task() need not be paired.
>
> So need remove end_exclusive() after queue_signal(). If could really
> return from queue_signal(), which meant stop_all_task() is not called (
> at least, not called in time), the next end_exclusive() would be issue.
>
> Also use TARGET_SIGSEGV instead of SIGSEGV, since queue_signal() is for
> TARGET_*, at present, queue_signal() is a normal function which may call
> force_sig(), or return (may kill pid or queue signal, then return).

It would be helpful to mention the affected target architecture
(and/or function name) in the commit message, because main.c covers
a lot of ground.

> Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
> ---
>  linux-user/main.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 8c70be4..a410a17 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -517,14 +517,12 @@ segv:
>      end_exclusive();
>      /* We get the PC of the entry address - which is as good as anything,
>         on a real kernel what you get depends on which mode it uses. */
> -    info.si_signo = SIGSEGV;
> +    info.si_signo = TARGET_SIGSEGV;

I think this is a correct bug fix, but it's not really related
to the main point of the patch (fixing end_exclusive()) and
there are actually a lot of instances of it in this file and
possibly others. Could you fix it (and those others) in a separate
patch, please?

>      info.si_errno = 0;
>      /* XXX: check env->error_code */
>      info.si_code = TARGET_SEGV_MAPERR;
>      info._sifields._sigfault._addr = env->exception.vaddress;
>      queue_signal(env, info.si_signo, &info);
> -
> -    end_exclusive();
>  }

This change is correct.

thanks
-- PMM

Re: [Qemu-devel] [PATCH] linux-user/main.c: Remove redundant end_exclusive()

[Chen Gang S]

On 1/23/15 18:20, Peter Maydell wrote:
> On 23 January 2015 at 10:17, Chen Gang S <gang.chen@sunrus.com.cn> wrote:
>> start/end_exclusive() need be pairs, except the start_exclusive() in
>> stop_all_tasks() which is only used by force_sig(), which will be abort.
>> So at present, start_exclusive() in stop_all_task() need not be paired.
>>
>> So need remove end_exclusive() after queue_signal(). If could really
>> return from queue_signal(), which meant stop_all_task() is not called (
>> at least, not called in time), the next end_exclusive() would be issue.
>>
>> Also use TARGET_SIGSEGV instead of SIGSEGV, since queue_signal() is for
>> TARGET_*, at present, queue_signal() is a normal function which may call
>> force_sig(), or return (may kill pid or queue signal, then return).
> 
> It would be helpful to mention the affected target architecture
> (and/or function name) in the commit message, because main.c covers
> a lot of ground.
> 

OK, thanks, I shall notice about it, next.

>> Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
>> ---
>>  linux-user/main.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/linux-user/main.c b/linux-user/main.c
>> index 8c70be4..a410a17 100644
>> --- a/linux-user/main.c
>> +++ b/linux-user/main.c
>> @@ -517,14 +517,12 @@ segv:
>>      end_exclusive();
>>      /* We get the PC of the entry address - which is as good as anything,
>>         on a real kernel what you get depends on which mode it uses. */
>> -    info.si_signo = SIGSEGV;
>> +    info.si_signo = TARGET_SIGSEGV;
> 
> I think this is a correct bug fix, but it's not really related
> to the main point of the patch (fixing end_exclusive()) and
> there are actually a lot of instances of it in this file and
> possibly others. Could you fix it (and those others) in a separate
> patch, please?
> 

OK, thanks, I shall send related patch for it within 2 days.

>>      info.si_errno = 0;
>>      /* XXX: check env->error_code */
>>      info.si_code = TARGET_SEGV_MAPERR;
>>      info._sifields._sigfault._addr = env->exception.vaddress;
>>      queue_signal(env, info.si_signo, &info);
>> -
>> -    end_exclusive();
>>  }
> 
> This change is correct.
> 

OK, thanks.

-- 
Chen Gang

Open, share, and attitude like air, water, and life which God blessed