From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Date: Fri, 17 Mar 2006 23:26:45 +0000 Subject: Re: [PATCH] Add SA_PERCPU_IRQ flag support Message-Id: <20060317152645.52112021.akpm@osdl.org> List-Id: References: <20060317003114.GA1735@sgi.com> In-Reply-To: <20060317003114.GA1735@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dimitri Sivanich Cc: torvalds@osdl.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, clameter@sgi.com, jes@sgi.com Dimitri Sivanich wrote: > > he generic request_irq/setup_irq code should support the SA_PERCPU_IRQ flag. > > Not sure why it was left out, but this patch adds that support. > > Signed-off-by: Dimitri Sivanich > > Index: linux/kernel/irq/manage.c > =================================> --- linux.orig/kernel/irq/manage.c 2006-03-16 14:05:27.957927445 -0600 > +++ linux/kernel/irq/manage.c 2006-03-16 14:06:02.283661867 -0600 > @@ -201,6 +201,9 @@ int setup_irq(unsigned int irq, struct i > * The following block of code has to be executed atomically > */ > spin_lock_irqsave(&desc->lock,flags); > + if (new->flags & SA_PERCPU_IRQ) { > + desc->status |= IRQ_PER_CPU; > + } > p = &desc->action; > if ((old = *p) != NULL) { > /* Can't share interrupts unless both agree to */ Yes, we're presently going in and needlessly taking desc->lock on every cpu-local interrupt. However it only appears to affect mmtimer.c at present. Shouldn't we also have a check in there, to make sure that all the other handlers off this IRQ agree about the per-cpuness of this interrupt? Your patch broke the x86 build, btw.. From: Dimitri Sivanich The generic request_irq/setup_irq code should support the SA_PERCPU_IRQ flag. Also, check that all handlers agree to do per-cpu IRQs. Signed-off-by: Dimitri Sivanich Signed-off-by: Andrew Morton --- kernel/irq/manage.c | 23 +++++++++++++++++++---- 1 files changed, 19 insertions(+), 4 deletions(-) diff -puN kernel/irq/manage.c~generic-irq-add-sa_percpu_irq-flag-support kernel/irq/manage.c --- 25/kernel/irq/manage.c~generic-irq-add-sa_percpu_irq-flag-support Fri Mar 17 15:06:44 2006 +++ 25-akpm/kernel/irq/manage.c Fri Mar 17 15:23:02 2006 @@ -204,10 +204,14 @@ int setup_irq(unsigned int irq, struct i p = &desc->action; if ((old = *p) != NULL) { /* Can't share interrupts unless both agree to */ - if (!(old->flags & new->flags & SA_SHIRQ)) { - spin_unlock_irqrestore(&desc->lock,flags); - return -EBUSY; - } + if (!(old->flags & new->flags & SA_SHIRQ)) + goto mismatch; + +#ifdef ARCH_HAS_IRQ_PER_CPU + /* All handlers must agree on per-cpuness */ + if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU)) + goto mismatch; +#endif /* add new interrupt at end of irq queue */ do { @@ -219,6 +223,11 @@ int setup_irq(unsigned int irq, struct i *p = new; +#ifdef ARCH_HAS_IRQ_PER_CPU + if (new->flags & SA_PERCPU_IRQ) + desc->status |= IRQ_PER_CPU; +#endif + if (!shared) { desc->depth = 0; desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | @@ -236,6 +245,12 @@ int setup_irq(unsigned int irq, struct i register_handler_proc(irq, new); return 0; + +mismatch: + spin_unlock_irqrestore(&desc->lock, flags); + printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__); + dump_stack(); + return -EBUSY; } #ifdef CONFIG_DEBUG_SHIRQ _