From 4bcdf1d0b652bc33d52f2322b77463e4dc58abf8 Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Fri, 9 Mar 2012 14:59:26 +0100 Subject: [PATCH] genirq: Get rid of unnecessary irqaction field in task_struct When a new thread handler is created, an irqaction is passed to it as data. Not only that irqaction is stored in task_struct by the handler for later use, but also a structure associated with the kernel thread keeps this value as long as the thread exists. This fix kicks irqaction out off task_struct. Yes, I introduce new bit field. But it allows not only to eliminate the duplicate, but also shortens size of task_struct. Reported-by: Oleg Nesterov Signed-off-by: Alexander Gordeev Link: http://lkml.kernel.org/r/20120309135925.GB2114@dhcp-26-207.brq.redhat.com Signed-off-by: Thomas Gleixner --- include/linux/sched.h | 10 +++++----- kernel/irq/manage.c | 19 +++++++++++-------- 2 files changed, 16 insertions(+), 13 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 7d379a6bfd8..07f537a371c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1319,6 +1319,11 @@ struct task_struct { unsigned sched_reset_on_fork:1; unsigned sched_contributes_to_load:1; +#ifdef CONFIG_GENERIC_HARDIRQS + /* IRQ handler threads */ + unsigned irq_thread:1; +#endif + pid_t pid; pid_t tgid; @@ -1427,11 +1432,6 @@ struct task_struct { * mempolicy */ spinlock_t alloc_lock; -#ifdef CONFIG_GENERIC_HARDIRQS - /* IRQ handler threads */ - struct irqaction *irqaction; -#endif - /* Protection of the PI data structures: */ raw_spinlock_t pi_lock; diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index c0730ad8a11..0fa3ce998ec 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -780,7 +780,7 @@ static int irq_thread(void *data) handler_fn = irq_thread_fn; sched_setscheduler(current, SCHED_FIFO, ¶m); - current->irqaction = action; + current->irq_thread = 1; while (!irq_wait_for_interrupt(action)) { @@ -818,10 +818,10 @@ static int irq_thread(void *data) irq_finalize_oneshot(desc, action, true); /* - * Clear irqaction. Otherwise exit_irq_thread() would make + * Clear irq_thread. Otherwise exit_irq_thread() would make * fuzz about an active irq thread going into nirvana. */ - current->irqaction = NULL; + current->irq_thread = 0; return 0; } @@ -832,27 +832,30 @@ void exit_irq_thread(void) { struct task_struct *tsk = current; struct irq_desc *desc; + struct irqaction *action; - if (!tsk->irqaction) + if (!tsk->irq_thread) return; + action = kthread_data(tsk); + printk(KERN_ERR "exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n", - tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq); + tsk->comm ? tsk->comm : "", tsk->pid, action->irq); - desc = irq_to_desc(tsk->irqaction->irq); + desc = irq_to_desc(action->irq); /* * Prevent a stale desc->threads_oneshot. Must be called * before setting the IRQTF_DIED flag. */ - irq_finalize_oneshot(desc, tsk->irqaction, true); + irq_finalize_oneshot(desc, action, true); /* * Set the THREAD DIED flag to prevent further wakeups of the * soon to be gone threaded handler. */ - set_bit(IRQTF_DIED, &tsk->irqaction->flags); + set_bit(IRQTF_DIED, &action->flags); } static void irq_setup_forced_threading(struct irqaction *new) -- 2.46.0