Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq/core changes for v3.4 from Ingo Molnar

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Remove paranoid warnons and bogus fixups
  genirq: Flush the irq thread on synchronization
  genirq: Get rid of unnecessary IRQTF_DIED flag
  genirq: No need to check IRQTF_DIED before stopping a thread handler
  genirq: Get rid of unnecessary irqaction field in task_struct
  genirq: Fix incorrect check for forced IRQ thread handler
  softirq: Reduce invoke_softirq() code duplication
  genirq: Fix long-term regression in genirq irq_set_irq_type() handling
  x86-32/irq: Don't switch to irq stack for a user-mode irq

8 files changed, 66 insertions, 82 deletions

diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 40fc86161d92..58b7f27cb3e9 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -100,13 +100,8 @@ execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
         irqctx->tinfo.task = curctx->tinfo.task;
         irqctx->tinfo.previous_esp = current_stack_pointer;
 
-        /*
-         * Copy the softirq bits in preempt_count so that the
-         * softirq checks work in the hardirq context.
-         */
-        irqctx->tinfo.preempt_count =
-                (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
-                (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
+        /* Copy the preempt_count so that the [soft]irq checks work. */
+        irqctx->tinfo.preempt_count = curctx->tinfo.preempt_count;
 
         if (unlikely(overflow))
                 call_on_stack(print_stack_overflow, isp);
@@ -196,7 +191,7 @@ bool handle_irq(unsigned irq, struct pt_regs *regs)
         if (unlikely(!desc))
                 return false;
 
-        if (!execute_on_irq_stack(overflow, desc, irq)) {
+        if (user_mode_vm(regs) || !execute_on_irq_stack(overflow, desc, irq)) {
                 if (unlikely(overflow))
                         print_stack_overflow();
                 desc->handle_irq(irq, desc);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f58889b8a608..e345163da657 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/exit.c b/kernel/exit.c
index 4b4042f9bc6a..752d2c0abd19 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -935,8 +935,6 @@ void do_exit(long code)
                 schedule();
         }
 
-        exit_irq_thread();
-
         exit_signals(tsk);  /* sets PF_EXITING */
         /*
          * tsk->flags are checked in the futex code to protect against
@@ -945,6 +943,8 @@ void do_exit(long code)
         smp_mb();
         raw_spin_unlock_wait(&tsk->pi_lock);
 
+        exit_irq_thread();
+
         if (unlikely(in_atomic()))
                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
                                 current->comm, task_pid_nr(current),
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index fb7db75ee0c8..25784d630a12 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -61,8 +61,7 @@ int irq_set_irq_type(unsigned int irq, unsigned int type)
                 return -EINVAL;
 
         type &= IRQ_TYPE_SENSE_MASK;
-        if (type != IRQ_TYPE_NONE)
-                ret = __irq_set_trigger(desc, irq, type);
+        ret = __irq_set_trigger(desc, irq, type);
         irq_put_desc_busunlock(desc, flags);
         return ret;
 }
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 470d08c82bbe..6ff84e6a954c 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -60,7 +60,7 @@ static void irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
          * device interrupt, so no irq storm is lurking. If the
          * RUNTHREAD bit is already set, nothing to do.
          */
-        if (test_bit(IRQTF_DIED, &action->thread_flags) ||
+        if ((action->thread->flags & PF_EXITING) ||
             test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
                 return;
 
@@ -110,6 +110,18 @@ static void irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
          * threads_oneshot untouched and runs the thread another time.
          */
         desc->threads_oneshot |= action->thread_mask;
+
+        /*
+         * We increment the threads_active counter in case we wake up
+         * the irq thread. The irq thread decrements the counter when
+         * it returns from the handler or in the exit path and wakes
+         * up waiters which are stuck in synchronize_irq() when the
+         * active count becomes zero. synchronize_irq() is serialized
+         * against this code (hard irq handler) via IRQS_INPROGRESS
+         * like the finalize_oneshot() code. See comment above.
+         */
+        atomic_inc(&desc->threads_active);
+
         wake_up_process(action->thread);
 }
 
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 40378ff877e7..8e5c56b3b7d9 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -20,14 +20,12 @@ extern bool noirqdebug;
 /*
  * Bits used by threaded handlers:
  * IRQTF_RUNTHREAD - signals that the interrupt handler thread should run
- * IRQTF_DIED      - handler thread died
  * IRQTF_WARNED    - warning "IRQ_WAKE_THREAD w/o thread_fn" has been printed
  * IRQTF_AFFINITY  - irq thread is requested to adjust affinity
  * IRQTF_FORCED_THREAD  - irq action is force threaded
  */
 enum {
         IRQTF_RUNTHREAD,
-        IRQTF_DIED,
         IRQTF_WARNED,
         IRQTF_AFFINITY,
         IRQTF_FORCED_THREAD,
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0f0d4704ddd8..b0ccd1ac2d6a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -759,6 +759,13 @@ static irqreturn_t irq_thread_fn(struct irq_desc *desc,
         return ret;
 }
 
+static void wake_threads_waitq(struct irq_desc *desc)
+{
+        if (atomic_dec_and_test(&desc->threads_active) &&
+            waitqueue_active(&desc->wait_for_threads))
+                wake_up(&desc->wait_for_threads);
+}
+
 /*
  * Interrupt handler thread
  */
@@ -771,57 +778,41 @@ static int irq_thread(void *data)
         struct irq_desc *desc = irq_to_desc(action->irq);
         irqreturn_t (*handler_fn)(struct irq_desc *desc,
                         struct irqaction *action);
-        int wake;
 
-        if (force_irqthreads & test_bit(IRQTF_FORCED_THREAD,
+        if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
                                         &action->thread_flags))
                 handler_fn = irq_forced_thread_fn;
         else
                 handler_fn = irq_thread_fn;
 
         sched_setscheduler(current, SCHED_FIFO, &param);
-        current->irqaction = action;
+        current->irq_thread = 1;
 
         while (!irq_wait_for_interrupt(action)) {
+                irqreturn_t action_ret;
 
                 irq_thread_check_affinity(desc, action);
 
-                atomic_inc(&desc->threads_active);
+                action_ret = handler_fn(desc, action);
+                if (!noirqdebug)
+                        note_interrupt(action->irq, desc, action_ret);
 
-                raw_spin_lock_irq(&desc->lock);
-                if (unlikely(irqd_irq_disabled(&desc->irq_data))) {
-                        /*
-                         * CHECKME: We might need a dedicated
-                         * IRQ_THREAD_PENDING flag here, which
-                         * retriggers the thread in check_irq_resend()
-                         * but AFAICT IRQS_PENDING should be fine as it
-                         * retriggers the interrupt itself --- tglx
-                         */
-                        desc->istate |= IRQS_PENDING;
-                        raw_spin_unlock_irq(&desc->lock);
-                } else {
-                        irqreturn_t action_ret;
-
-                        raw_spin_unlock_irq(&desc->lock);
-                        action_ret = handler_fn(desc, action);
-                        if (!noirqdebug)
-                                note_interrupt(action->irq, desc, action_ret);
-                }
-
-                wake = atomic_dec_and_test(&desc->threads_active);
-
-                if (wake && waitqueue_active(&desc->wait_for_threads))
-                        wake_up(&desc->wait_for_threads);
+                wake_threads_waitq(desc);
         }
 
-        /* Prevent a stale desc->threads_oneshot */
-        irq_finalize_oneshot(desc, action, true);
-
         /*
-         * Clear irqaction. Otherwise exit_irq_thread() would make
+         * This is the regular exit path. __free_irq() is stopping the
+         * thread via kthread_stop() after calling
+         * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
+         * oneshot mask bit can be set. We cannot verify that as we
+         * cannot touch the oneshot mask at this point anymore as
+         * __setup_irq() might have given out currents thread_mask
+         * again.
+         *
+         * 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 +823,28 @@ 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.
+         * If IRQTF_RUNTHREAD is set, we need to decrement
+         * desc->threads_active and wake possible waiters.
          */
-        irq_finalize_oneshot(desc, tsk->irqaction, true);
+        if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
+                wake_threads_waitq(desc);
 
-        /*
-         * Set the THREAD DIED flag to prevent further wakeups of the
-         * soon to be gone threaded handler.
-         */
-        set_bit(IRQTF_DIED, &tsk->irqaction->flags);
+        /* Prevent a stale desc->threads_oneshot */
+        irq_finalize_oneshot(desc, action, true);
 }
 
 static void irq_setup_forced_threading(struct irqaction *new)
@@ -1135,8 +1127,7 @@ out_thread:
                 struct task_struct *t = new->thread;
 
                 new->thread = NULL;
-                if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
-                        kthread_stop(t);
+                kthread_stop(t);
                 put_task_struct(t);
         }
 out_mput:
@@ -1246,8 +1237,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
 #endif
 
         if (action->thread) {
-                if (!test_bit(IRQTF_DIED, &action->thread_flags))
-                        kthread_stop(action->thread);
+                kthread_stop(action->thread);
                 put_task_struct(action->thread);
         }
 
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 4eb3a0fa351e..c82d95a022ef 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -310,31 +310,21 @@ void irq_enter(void)
         __irq_enter();
 }
 
-#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
 static inline void invoke_softirq(void)
 {
-        if (!force_irqthreads)
+        if (!force_irqthreads) {
+#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
                 __do_softirq();
-        else {
-                __local_bh_disable((unsigned long)__builtin_return_address(0),
-                                SOFTIRQ_OFFSET);
-                wakeup_softirqd();
-                __local_bh_enable(SOFTIRQ_OFFSET);
-        }
-}
 #else
-static inline void invoke_softirq(void)
-{
-        if (!force_irqthreads)
                 do_softirq();
-        else {
+#endif
+        } else {
                 __local_bh_disable((unsigned long)__builtin_return_address(0),
                                 SOFTIRQ_OFFSET);
                 wakeup_softirqd();
                 __local_bh_enable(SOFTIRQ_OFFSET);
         }
 }
-#endif
 
 /*
  * Exit an interrupt context. Process softirqs if needed and possible: