-----Original Message----- From: Gaurav Dhiman [mailto:gaurav4lkg@xxxxxxxxx] Sent: Monday, August 29, 2005 11:59 AM To: Aggarwal, Vikas (OFT) Cc: Hemant Mohapatra; kernelnewbies Subject: Re: synchronisation question On 8/29/05, Aggarwal, Vikas (OFT) <Vikas.Aggarwal@xxxxxxxxxxxxxxx> wrote: > -------------------------------------------------------- > This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. > > > -----Original Message----- > > From: kernelnewbies-bounce@xxxxxxxxxxxx > [mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of Hemant Mohapatra > Sent: Sunday, August 28, 2005 2:31 AM > To: Gaurav Dhiman > Cc: kernelnewbies > Subject: Re: synchronisation question > > On 8/27/05, Gaurav Dhiman <gaurav4lkg@xxxxxxxxx> wrote: > > > Are you sure of it that cli()/sti() disable the interrupts on all > > processors, i think it only disables the interrupts on local CPU. Well > > the cli() function is defined as follows in include/linux/interrupt.h > > Yup, my bad. kernel 2.6 and above do not allow global interrupt > disables. Thanks for pointing it out. > > Please clear this to me more-- > Won't there be any synchronization issue between the interrupt-handler > context on CPU1 and process context of CPU0? For handling such situation where you manupulate the common data structure from both interrupt context and process context and that too on SMP machines, you use spin_lock_irqsave() and spin_unlock_irqrestore() functions. If you have UP machine then using only cli() / local_irq_disable() and sti() / local_irq_enable() function will work, no need to use the spinlocks in that case. Does that mean calling spin_lock_irqsave() from CPU0/process-context can disable the CPU1/interrupt-context? -Gaurav > > > > > ./h > -- > Operating Systems and Computer Architecture Research - University of > Cincinnati > http://www.ececs.uc.edu/~mohapth > > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
