hi,
El Fri, 16 Feb 2007 14:50:44 +0530
"Ganesh PS" <ganesh.p7@xxxxxxxxx> ha escrit:
> Hi i am facing the following problem while running my kernel module:
>
> The code is:
> --------------
> struct timer_list myTimer;
> void gen_sig(void){
> struct task_struct *p=NULL;
> p=kmalloc(sizeof(struct task_struct), GFP_KERNEL);
>
> p = find_task_by_pid(pid); /*Received from a user program through
> ioctl()*/
>
> if (p == NULL) {
> printk("Unable to find task for process id %d\n",pid);
> return;
> }
>
> if ( send_sig(SIG_NO,p,0) != 0 ) { /* SIG_NO=51 */
> printk("Sending signal failed . . .\n");
> }
>
> myTimer.function = (void*)gen_sig;
> myTimer.expires = jiffies + TIMER_REFRESH_SUBSCRIBED_TABLE;
> add_timer (&myTimer);
> return;
> }
> static int watchdog_init (void) {
> myTimer.function = (void*)gen_sig;
> myTimer.expires = TIMER_REFRESH_SUBSCRIBED_TABLE; /*Value is 1*/
> add_timer (&myTimer);
> return 0;
> }
> int init_module(void){
> init_timer (&myTimer);
> watchdog_init();
> }
>
> The code is working fine but it's giving the following message in
> "dmesg"
> ----------------------------------------------------------------------
> Debug: sleeping function called from invalid context at
> mm/slab.c:2055 in_atomic():1, irqs_disabled():0 [<c011d475>]
> __might_sleep+0x95/0xb0 [<c0158820>] kmem_cache_alloc+0x50/0x60
> [<d02bc000>] gen_sig+0x0/0xc0 [sighnd]
> [<d02bc012>] generate_signal+0x12/0xc0 [sighnd]
> [<c013f0b0>] autoremove_wake_function+0x0/0x50
> [<c012c57c>] run_timer_softirq+0xfc/0x3e0
> [<c014a592>] handle_IRQ_event+0x32/0x70
> [<c0179454>] vfs_read+0xe4/0x130
> [<c0127842>] __do_softirq+0x42/0x90
> [<c01278b7>] do_softirq+0x27/0x30
> [<c010568b>] do_IRQ+0x3b/0x70
> [<c0103ae2>] common_interrupt+0x1a/0x20
> ---------------------------------------------------------------------
> This message comes on repeatedly and after some times the module
> hangs up.
>
> Same error occurs for every function that is being called through the
> timer.
>
> Is it wrong to call functions through timer in kernel?. Please give me
> suggestions to solve this problem.
you cannot sleep in interrupt context (timer code is interrupt
context), the function kmalloc might sleep if not invoked with
GFP_ATOMIC flag.
btw, avoid doing heavy tasks in timer code, use workqueues (that execute
in process context) or kernel threads (also in process context)
regards,
topi
> Thanks
> Ganesh
> ganesh.p7[at]gmail.com
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