From: Martin Schwidefsky <[EMAIL PROTECTED]>
From: Heiko Carstens <[EMAIL PROTECTED]>
From: Ursula Braun <[EMAIL PROTECTED]>
Calling smp_call_function can lead to a deadlock if it is called
from tasklet context.
Fixing this deadlock requires to move the smp_call_function from the
tasklet context to a work queue. To do that queue the path pending
interrupts to a separate list and move the path cleanup out of
iucv_path_sever to iucv_path_connect and iucv_path_pending.
This creates a new requirement for iucv_path_connect: it may not be
called from tasklet context anymore.
Also fixed compile problem for CONFIG_HOTPLUG_CPU=n and
another one when walking the cpu_online mask. When doing this,
we must disable cpu hotplug.
Signed-off-by: Frank Pavlic <[EMAIL PROTECTED]>
Signed-off-by: Martin Schwidefsky <[EMAIL PROTECTED]>
---
include/net/iucv/iucv.h |2
net/iucv/iucv.c | 207 ++--
2 files changed, 133 insertions(+), 76 deletions(-)
diff --git a/include/net/iucv/iucv.h b/include/net/iucv/iucv.h
index 746e741..fd70adb 100644
--- a/include/net/iucv/iucv.h
+++ b/include/net/iucv/iucv.h
@@ -16,7 +16,7 @@
* completed a register, it can exploit the other functions.
* For furthur reference on all IUCV functionality, refer to the
* CP Programming Services book, also available on the web thru
- * www.ibm.com/s390/vm/pubs, manual # SC24-5760
+ * www.vm.ibm.com/pubs, manual # SC24-6084
*
* Definition of Return Codes
* - All positive return codes including zero are reflected back
diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index 1b10d57..903bdb6 100644
--- a/net/iucv/iucv.c
+++ b/net/iucv/iucv.c
@@ -90,20 +90,43 @@ struct iucv_irq_data {
u32 res2[8];
};
-struct iucv_work {
+struct iucv_irq_list {
struct list_head list;
struct iucv_irq_data data;
};
-static LIST_HEAD(iucv_work_queue);
-static DEFINE_SPINLOCK(iucv_work_lock);
-
static struct iucv_irq_data *iucv_irq_data;
static cpumask_t iucv_buffer_cpumask = CPU_MASK_NONE;
static cpumask_t iucv_irq_cpumask = CPU_MASK_NONE;
-static void iucv_tasklet_handler(unsigned long);
-static DECLARE_TASKLET(iucv_tasklet, iucv_tasklet_handler,0);
+/*
+ * Queue of interrupt buffers lock for delivery via the tasklet
+ * (fast but can't call smp_call_function).
+ */
+static LIST_HEAD(iucv_task_queue);
+
+/*
+ * The tasklet for fast delivery of iucv interrupts.
+ */
+static void iucv_tasklet_fn(unsigned long);
+static DECLARE_TASKLET(iucv_tasklet, iucv_tasklet_fn,0);
+
+/*
+ * Queue of interrupt buffers for delivery via a work queue
+ * (slower but can call smp_call_function).
+ */
+static LIST_HEAD(iucv_work_queue);
+
+/*
+ * The work element to deliver path pending interrupts.
+ */
+static void iucv_work_fn(struct work_struct *work);
+static DECLARE_WORK(iucv_work, iucv_work_fn);
+
+/*
+ * Spinlock protecting task and work queue.
+ */
+static DEFINE_SPINLOCK(iucv_queue_lock);
enum iucv_command_codes {
IUCV_QUERY = 0,
@@ -147,10 +170,10 @@ static unsigned long iucv_max_pathid;
static DEFINE_SPINLOCK(iucv_table_lock);
/*
- * iucv_tasklet_cpu: contains the number of the cpu executing the tasklet.
- * Needed for iucv_path_sever called from tasklet.
+ * iucv_active_cpu: contains the number of the cpu executing the tasklet
+ * or the work handler. Needed for iucv_path_sever called from tasklet.
*/
-static int iucv_tasklet_cpu = -1;
+static int iucv_active_cpu = -1;
/*
* Mutex and wait queue for iucv_register/iucv_unregister.
@@ -449,17 +472,19 @@ static void iucv_setmask_mp(void)
{
int cpu;
+ preempt_disable();
for_each_online_cpu(cpu)
/* Enable all cpus with a declared buffer. */
if (cpu_isset(cpu, iucv_buffer_cpumask) &&
!cpu_isset(cpu, iucv_irq_cpumask))
smp_call_function_on(iucv_allow_cpu, NULL, 0, 1, cpu);
+ preempt_enable();
}
/**
* iucv_setmask_up
*
- * Allow iucv interrupts on a single cpus.
+ * Allow iucv interrupts on a single cpu.
*/
static void iucv_setmask_up(void)
{
@@ -493,8 +518,10 @@ static int iucv_enable(void)
goto out;
/* Declare per cpu buffers. */
rc = -EIO;
+ preempt_disable();
for_each_online_cpu(cpu)
smp_call_function_on(iucv_declare_cpu, NULL, 0, 1, cpu);
+ preempt_enable();
if (cpus_empty(iucv_buffer_cpumask))
/* No cpu could declare an iucv buffer. */
goto out_path;
@@ -519,7 +546,6 @@ static void iucv_disable(void)
kfree(iucv_path_table);
}
-#ifdef CONFIG_HOTPLUG_CPU
static int __cpuinit iucv_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
@@ -565,7 +591,6 @@ static int __cpuinit iucv_cpu_notify(struct notifier_block
*self,
static struct notifier_block iucv_cpu_notifier = {
.notifier_call = iucv_cpu_notify,
};
-#endif
/**
