Defination of Flag CONFIG_DEBUG_SPINLOCK_SLEEP in AS4 UP1

[shahid shaikh]

Hi all,
While doing insmod for a psuedo driver, kernel is dumping a stack because
sleep function is called.
My init_module function for psuedo driver calls add_disk to register admin
device.
In add_disk(), kernel is allocating memory using kmalloc with flag
GFP_KERNEL. This is hardcoded in kernel code for add_disk.

Whenever kernel inserts any module or driver it disable all interrupts. But
allocating memory with GFP_KERNEL  flag may sleep. This becomes self
contradicting. Hence an invalid context.
Through kmalloc(), might_sleep_if( flag & GFP_WAIT ) function is called
where flag is GFP_KERNEL.
At this, sleep function is called.
Sleep function have been defined differently depending on defination of
CONFIG_DEBUG_SPINLOCK_SLEEP flag.
The above flag is defined in AS4 UP1. If the flag is defined, might_sleep()
function calls sleep function and then calls reschedule function.
If not defined, might_sleep() function directly calls reschedule function.
In sleep function if irqs_disabled() returns 1, it dumps stack.
irqs_disabled() returns 1 when irqs are disabled.

What we should do to avoid the above scenario?

GFP_KERNEL flag in kmalloc code is hard coded. Can't change that.

We have to call add_disk from our init_module to register admin device for
our psuedo driver.

We tried by enabling irqs before calling add_disk using kernel api
local_irq_enable(). It works fine.
But is it correct to enable irqs in a kernel module?
After add_disk we even restored it back using kernel api
local_irq_disable().

Or is there any other way around thorugh which we can avoid the above
scenario?

Warm Regards,
Shahid Shaikh.





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