An interrupt handler can call function sprintf()?

[fl]

Hi,

I remember it said that C lib function printf() cannot be called in a device driver in Linux. Today I come across the following code snippet. I wonder that sprintf function can be called in the interrupt function?

Interrupt function is part of device driver or not?

Please clarify those concepts if you can. Thanks.






......
irqreturn_t short_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
struct timeval tv;
int written;

do_gettimeofday(&tv);
/* Write a 16 byte record. Assume PAGE_SIZE is a multiple of 16 */
written = sprintf((char *)short_head,"%08u.%06u\n",
(int)(tv.tv_sec % 100000000), (int)(tv.tv_usec));
BUG_ON(written != 16);
short_incr_bp(&short_head, written);
wake_up_interruptible(&short_queue); /* awake any reading process */
return IRQ_HANDLED;
}

[Jerry Peters]

fl <rxj...@gmail.com> wrote:
> Hi,
>
> I remember it said that C lib function printf() cannot be called in a device driver in Linux. Today I come across the following code snippet. I wonder that sprintf function can be called in the interrupt function?
>

It can't, because it writes to a file, stdout. Sprintf "writes" to an
existing string so there's no i/o. Sprintf is just a convenient way to
construct a fancy formatted string.

There is another function, kprintf, which can be used similiarly to
printf, but it wrties to a kernel buffer.

Jerry

[Jerry Peters]

Jerry Peters <je...@example.invalid> wrote:
> fl <rxj...@gmail.com> wrote:
>> Hi,
>>
>> I remember it said that C lib function printf() cannot be called in a device driver in Linux. Today I come across the following code snippet. I wonder that sprintf function can be called in the interrupt function?
>>
> It can't, because it writes to a file, stdout. Sprintf "writes" to an
> existing string so there's no i/o. Sprintf is just a convenient way to
> construct a fancy formatted string.
>
> There is another function, kprintf, which can be used similiarly to
> printf, but it wrties to a kernel buffer.

Oops, meant printk, not kprintf.

Jerry