help tasklist_lock

help tasklist_lock

[Giacomo]

Good morning to all!
I've written a module which needs to lock the tasklist_lock to read
the processes and get their pid.

Before kernel source 2.6.18 the symbol tasklist_lock was exported inside the
file fork.c.
With kernel 2.6.18, such symbol is no more exported, albeit a large number of
other source files use it.

My code does not compile any more and it says unexported symbol during
the compilation.

How can i do it?
Is there a way to make my module see the tasklist_lock?

The documentation of the kernel says:

What:   remove EXPORT_SYMBOL(tasklist_lock)
When:   August 2006
Files:  kernel/fork.c
Why:    tasklist_lock protects the kernel internal task list.  Modules have
       no business looking at it, and all instances in drivers have been due
       to use of too-lowlevel APIs.  Having this symbol exported prevents
       moving to more scalable locking schemes for the task list.

while my code does simply the following:

struct task_struct *get_uid_from_pid(const pid_t uspace_pid)
{
       struct task_struct *task;
       /* task list must not change while we are reading!
        * We are not in atomic */
       read_lock(&tasklist_lock);
       for_each_process(task)
       {
               if (task->pid == uspace_pid)
                 {
                         read_unlock(&tasklist_lock);
                         return task;
                 }
       }
       read_unlock(&tasklist_lock);
       return NULL;
}

Thanks a lot for any suggestion.

Giacomo S.
-- 
Giacomo S.
http://www.giacomos.it
 
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help tasklist_lock

[Giacomo]

Good morning to all!
I've written a module which needs to lock the tasklist_lock to read
the processes and get their pid.

Before kernel source 2.6.18 the symbol tasklist_lock was exported inside the
file fork.c.
With kernel 2.6.18, such symbol is no more exported, albeit a large number of
other source files use it.

My code does not compile any more and it says unexported symbol during
the compilation.

How can i do it?
Is there a way to make my module see the tasklist_lock?

The documentation of the kernel says:

What:   remove EXPORT_SYMBOL(tasklist_lock)
When:   August 2006
Files:  kernel/fork.c
Why:    tasklist_lock protects the kernel internal task list.  Modules have
       no business looking at it, and all instances in drivers have been due
       to use of too-lowlevel APIs.  Having this symbol exported prevents
       moving to more scalable locking schemes for the task list.

while my code does simply the following:

struct task_struct *get_uid_from_pid(const pid_t uspace_pid)
{
       struct task_struct *task;
       /* task list must not change while we are reading!
        * We are not in atomic */
       read_lock(&tasklist_lock);
       for_each_process(task)
       {
               if (task->pid == uspace_pid)
                 {
                         read_unlock(&tasklist_lock);
                         return task;
                 }
       }
       read_unlock(&tasklist_lock);
       return NULL;
}

Thanks a lot for any suggestion.

Giacomo S.
--
Giacomo S.
http://www.giacomos.it

- - - - - - - - - - - - - - - - - - - - - -

Proteggi il tuo PC provando il mio semplice FIREWALL:
http://www.giacomos.it/ipfire

mailto:
delleceste@gmail.com
giacomo.strangolino@elettra.trieste.it
jacum@libero.it

- - - - - - - - - - - - - - - - - - - - - -

 . ''  `.

:   :'    :

 `.  ` '
    `- Debian GNU/Linux -- The power of freedom
        http://www.debian.org

-------------------------------------------------------

-- 
Giacomo S.
http://www.giacomos.it
 
- - - - - - - - - - - - - - - - - - - - - -

Proteggi il tuo PC provando il mio semplice FIREWALL:
http://www.giacomos.it/ipfire

mailto:
delleceste@gmail.com
giacomo.strangolino@elettra.trieste.it
jacum@libero.it

- - - - - - - - - - - - - - - - - - - - - -

 . ''  `.
:   :'    :
 `.  ` '
    `- Debian GNU/Linux -- The power of freedom
        http://www.debian.org

Re: help tasklist_lock

[Patrick McHardy]

Giacomo wrote:
> 
> Good morning to all!
> I've written a module which needs to lock the tasklist_lock to read
> the processes and get their pid.

Please stop flooding the list with the same mail over and over.

help tasklist_lock

[Giacomo]

Good morning to all!
I've written a module which needs to lock the tasklist_lock to read
the processes and get their pid.

Before kernel source 2.6.18 the symbol tasklist_lock was exported inside the
file fork.c.
With kernel 2.6.18, such symbol is no more exported, albeit a large number of
other source files use it.

My code does not compile any more and it says unexported symbol during
the compilation.

How can i do it?
Is there a way to make my module see the tasklist_lock?

The documentation of the kernel says:

What:   remove EXPORT_SYMBOL(tasklist_lock)
When:   August 2006
Files:  kernel/fork.c
Why:    tasklist_lock protects the kernel internal task list.  Modules have
       no business looking at it, and all instances in drivers have been due
       to use of too-lowlevel APIs.  Having this symbol exported prevents
       moving to more scalable locking schemes for the task list.

while my code does simply the following:

struct task_struct *get_uid_from_pid(const pid_t uspace_pid)
{
       struct task_struct *task;
       /* task list must not change while we are reading!
        * We are not in atomic */
       read_lock(&tasklist_lock);
       for_each_process(task)
       {
               if (task->pid == uspace_pid)
                 {
                         read_unlock(&tasklist_lock);
                         return task;
                 }
       }
       read_unlock(&tasklist_lock);
       return NULL;
}

Thanks a lot for any suggestion.

Giacomo S.

-- 
Giacomo S.
http://www.giacomos.it

- - - - - - - - - - - - - - - - - - - - - -

Proteggi il tuo PC provando il mio semplice FIREWALL:
http://www.giacomos.it/ipfire

mailto:
delleceste@gmail.com
giacomo.strangolino@elettra.trieste.it
jacum@libero.it

- - - - - - - - - - - - - - - - - - - - - -

 . ''  `.
:   :'    :
 `.  ` '
    `- Debian GNU/Linux -- The power of freedom
        http://www.debian.org