From mboxrd@z Thu Jan 1 00:00:00 1970 From: zertsekel@gmail.com (Kosta Zertsekel) Date: Sun, 26 Feb 2012 14:11:54 +0200 Subject: About interrupt handler In-Reply-To: References: Message-ID: To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org On Fri, Feb 24, 2012 at 11:18 PM, Dave Hylands wrote: > HI Kosta, > > On Fri, Feb 24, 2012 at 1:08 PM, Dave Hylands wrote: >> Hi Kosta, >> >> On Fri, Feb 24, 2012 at 1:19 AM, Kosta Zertsekel wrote: >>>>> I'm begin to learn the Kernel and i'm reading <>>>> development>>.It says "This is an important point, always keep in mind that >>>>> all interrupt handler has interrupted other code(possibly even another >>>>> interrupt handler on a different line)".What i am not able to understand is >>>>> how a interrupt handler be interrupted ? DID NOT it uninterrupted? >>>> >>>> It depends on the architecture and the interrupt controller being >>>> used, and the driver code itself. >>>> >>>> Normally, when an interrupt fires, that particular interrupt will be >>>> masked and your own handler won't interrupt itself, but you may very >>>> well be interrupted by other interrupts. >>> >>> Can you please point out some code for explanation? >> >> Could you be a bit more specific about what example you're looking for? > > I also believe that things have changed (since I looked at this in any > detail). It seems that interrupts are now run with other interrupts > disabled. > See: http://lwn.net/Articles/364583/ and look at the IRQF_DISABLED discussion. Oh, yes, it seems it does as of kernel 3.3.0. But I fail to accept the argument... What happens for NAPI drivers stalling the kernel - *nobody* can interrupt them... Is there some reliable IRQ deep dive explanation - I need one just to wrap my mind over the issue? Thanks, --- KostaZ