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From devnull@lkml.org Sun May 5 11:41:59 2024 Delivery-date: Wed, 07 Mar 2007 19:29:03 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992489AbXCGT2e (ORCPT ); Wed, 7 Mar 2007 14:28:34 -0500 Received: from wr-out-0506.google.com ([64.233.184.234]:22919 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992486AbXCGT2d convert rfc822-to-8bit (ORCPT ); Wed, 7 Mar 2007 14:28:33 -0 Received: by wr-out-0506.google.com with SMTP id 37so498967wra for ; Wed, 07 Mar 2007 11:28:32 -0800 (PST) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=hNHrkeev DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=nwh/16Cag/keWoqhWYu7I6CGA7okDNQZt+bttOD4fwVe0zt Received: by 10.114.94.1 with SMTP id r1mr2281289wab.1173295711681; Wed, 07 Mar 2007 11:28:31 -0800 (PST) Received: by 10.114.72.13 with HTTP; Wed, 7 Mar 2007 11:28:21 -0800 (PST) Message-Id: <1b2aacd80703071128v5227382do2277d0b85ca3b20c@mail.gmail.com> Date: Wed, 7 Mar 2007 11:28:21 -0800 From: "Luong Ngo" To: "linux-os (Dick Johnson)" Subject: Re: Sleeping thread not receive signal until it wakes up Cc: linux-kernel@vger.kernel.org In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <1b2aacd80703062131g6c8578fgf200dd05a502c49f@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org Hi Dick, Thanks for your response. In my ioctl in the kernel, I use interruptible_sleep_on to sleep on a queue and will be wake up by the the ISR routine when interrupt happens, so isn't interruptible_sleep_on supposed to be interruptable, from its name? I am using kernel 2.6.14. Thanks again, LNgo On 3/7/07, linux-os (Dick Johnson) wrote: > > On Wed, 7 Mar 2007, Luong Ngo wrote: > > > Hi all, > > > > I am having this problem. I have a process with 2 threads created. One > > of the thread will keep calling IOCTL to get information from the > > kernel and will be blocked if there is no new information. If there is > > information retured, the thread will be checked to see if any error > > happens and trigger an action. Since we have no way to know if the > > error is gone (Hardware provides no signal), so what we do is when > > trigger an action for the error, we will set an timer using alarm() > > and register a SIGALRM handler in the thread by using sigaction. After > > setting the alarm, the thread will loop back and call IOCTL, which > > could cause it to be put to sleep. The problem is the SIGALRM handler > > does not receive the SIGALRM while the thread is being blocked by > > IOCTL. And if we generated some event so that the IOCTL is returned > > with new information, the SIGALRM handler is invoked right away. > > However, as I read the manual, which says a thread/process should be > > waken up even when it sleeps if there is a signal delivered to it. Am > > I right? > > One thing I don't know it mattters or not is that I am not using > > sigwait to block the process and wait for signal because the thread > > need to go back to the IOCTL call and be slept on that. So I used > > sigaction to register the signal handler in hope that this handler wil > > be invoked by the kernel when there is an SIGALRM delivered to the > > thread. > > Could anyone tell me if I did something wrong and what is the correct > > way to achieve this task? I tried to avoid creating another thread > > which will call sigwait and block until the IOCTL thread send it > > explicitly a signal because I want to use timer. > > > > > > Thank you in advance, > > LNgo > > - > > Later versions of the kernel lock the kernel when an ioctl() is > entered. This means that if you sleep in the ioctl(), nothing > will get scheduled. > > You can do the following (possibly unsafe) in your ioctl(): > > int locked = kernel_locked(); > > ......... code > ......... code > > if(locked) // Before sleeping section > unlock_kernel(); > .......... sleeping code > if(locked) // After sleeping section > lock_kernel(); > > > > Cheers, > Dick Johnson > Penguin : Linux version 2.6.16.24 on an i686 machine (5592.71 BogoMips). > New book: http://www.AbominableFirebug.com/ > _ >  > > **************************************************************** > The information transmitted in this message is confidential and may be privileged. 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