Date: Sun, 20 Feb 2005 08:08:11 -0700 From: Scott <scottl@samsco.org> To: "Daniel O'Connor" <doconnor@gsoft.com.au> Cc: Peter Jeremy <PeterJeremy@optushome.com.au> Subject: Re: Signalling a process from a INTR_FAST handler Message-ID: <4218A7DB.1050705@samsco.org> In-Reply-To: <200502201805.43307.doconnor@gsoft.com.au> References: <20050220054251.GB28983@cirb503493.alcatel.com.au> <200502201805.43307.doconnor@gsoft.com.au>
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Daniel O'Connor wrote:
> On Sun, 20 Feb 2005 16:12, Peter Jeremy wrote:
>
>>I have a hardware interrupt handler that has to forward a signal to
>>userland and that I'd like to mark INTR_FAST. AFAIK, the normal way
>>to forward a signal is:
>> if ((p = pfind(sc->pid_to_signal)) != NULL) {
>> psignal(p, SIGUSR2);
>> PROC_UNLOCK(p);
>> }
>>
>>But pfind(9) does a PROC_LOCK() which implies it can sleep and therefore
>>can't be used by an INTR_FAST handler.
>>
>>Firstly, am I correct? If so, is there an alternative approach I can use?
>
>
> I think you are, and I think the only way to do it is to schedule another
> kernel [heavy] thread to do the wakeup.
>
You can shift the operation off to a fast taskqueue. This assumes that
latency between the interrupt and the signal delivery is not critical.
Scott
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