Piteball
/
android_kernel_samsung_msm8976
mirror of https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
1
1
Fork 0
Code Issues Projects Releases Wiki Activity

[AF_IUCV/IUCV]: smp_call_function deadlock 

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 <fpavlic@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Martin Schwidefsky 2007-04-28 23:03:59 -07:00 committed by David S. Miller
parent d0772b70fa
commit 04b090d50c
2 changed files with 133 additions and 74 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/iucv/iucv.h
View File

@ -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

205
net/iucv/iucv.c
View File

@ -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;
@ -584,48 +611,49 @@ static int iucv_sever_pathid(u16 pathid, u8 userdata[16])
return iucv_call_b2f0(IUCV_SEVER, parm);
}
#ifdef CONFIG_SMP
/**
* __iucv_cleanup_pathid
* __iucv_cleanup_queue
* @dummy: unused dummy argument
*
* Nop function called via smp_call_function to force work items from
* pending external iucv interrupts to the work queue.
*/
static void __iucv_cleanup_pathid(void *dummy)
static void __iucv_cleanup_queue(void *dummy)
{
}
#endif
/**
* iucv_cleanup_pathid
* @pathid: 16 bit pathid
* iucv_cleanup_queue
*
* Function called after a path has been severed to find all remaining
* work items for the now stale pathid. The caller needs to hold the
* iucv_table_lock.
*/
static void iucv_cleanup_pathid(u16 pathid)
static void iucv_cleanup_queue(void)
{
struct iucv_work *p, *n;
struct iucv_irq_list *p, *n;
/*
* Path is severed, the pathid can be reused immediatly on
* a iucv connect or a connection pending interrupt.
* iucv_path_connect and connection pending interrupt will
* wait until the iucv_table_lock is released before the
* recycled pathid enters the system.
* Force remaining interrupts to the work queue, then
* scan the work queue for items of this path.
* When a path is severed, the pathid can be reused immediatly
* on a iucv connect or a connection pending interrupt. Remove
* all entries from the task queue that refer to a stale pathid
* (iucv_path_table[ix] == NULL). Only then do the iucv connect
* or deliver the connection pending interrupt. To get all the
* pending interrupts force them to the work queue by calling
* an empty function on all cpus.
*/
smp_call_function(__iucv_cleanup_pathid, NULL, 0, 1);
spin_lock_irq(&iucv_work_lock);
list_for_each_entry_safe(p, n, &iucv_work_queue, list) {
/* Remove work items for pathid except connection pending */
if (p->data.ippathid == pathid && p->data.iptype != 0x01) {
smp_call_function(__iucv_cleanup_queue, NULL, 0, 1);
spin_lock_irq(&iucv_queue_lock);
list_for_each_entry_safe(p, n, &iucv_task_queue, list) {
/* Remove stale work items from the task queue. */
if (iucv_path_table[p->data.ippathid] == NULL) {
list_del(&p->list);
kfree(p);
}
}
spin_unlock_irq(&iucv_work_lock);
spin_unlock_irq(&iucv_queue_lock);
}
/**
@ -684,7 +712,6 @@ void iucv_unregister(struct iucv_handler *handler, int smp)
iucv_sever_pathid(p->pathid, NULL);
iucv_path_table[p->pathid] = NULL;
list_del(&p->list);
iucv_cleanup_pathid(p->pathid);
iucv_path_free(p);
}
spin_unlock_bh(&iucv_table_lock);
@ -757,9 +784,9 @@ int iucv_path_connect(struct iucv_path *path, struct iucv_handler *handler,
union iucv_param *parm;
int rc;
preempt_disable();
if (iucv_tasklet_cpu != smp_processor_id())
spin_lock_bh(&iucv_table_lock);
BUG_ON(in_atomic());
spin_lock_bh(&iucv_table_lock);
iucv_cleanup_queue();
parm = percpu_ptr(iucv_param, smp_processor_id());
memset(parm, 0, sizeof(union iucv_param));
parm->ctrl.ipmsglim = path->msglim;
@ -794,9 +821,7 @@ int iucv_path_connect(struct iucv_path *path, struct iucv_handler *handler,
rc = -EIO;
}
}
if (iucv_tasklet_cpu != smp_processor_id())
spin_unlock_bh(&iucv_table_lock);
preempt_enable();
spin_unlock_bh(&iucv_table_lock);
return rc;
}
@ -867,15 +892,14 @@ int iucv_path_sever(struct iucv_path *path, u8 userdata[16])
preempt_disable();
if (iucv_tasklet_cpu != smp_processor_id())
if (iucv_active_cpu != smp_processor_id())
spin_lock_bh(&iucv_table_lock);
rc = iucv_sever_pathid(path->pathid, userdata);
if (!rc) {
iucv_path_table[path->pathid] = NULL;
list_del_init(&path->list);
iucv_cleanup_pathid(path->pathid);
}
if (iucv_tasklet_cpu != smp_processor_id())
if (iucv_active_cpu != smp_processor_id())
spin_unlock_bh(&iucv_table_lock);
preempt_enable();
return rc;
@ -1244,8 +1268,7 @@ static void iucv_path_complete(struct iucv_irq_data *data)
struct iucv_path_complete *ipc = (void *) data;
struct iucv_path *path = iucv_path_table[ipc->ippathid];
BUG_ON(!path || !path->handler);
if (path->handler->path_complete)
if (path && path->handler && path->handler->path_complete)
path->handler->path_complete(path, ipc->ipuser);
}
@ -1273,14 +1296,14 @@ static void iucv_path_severed(struct iucv_irq_data *data)
struct iucv_path_severed *ips = (void *) data;
struct iucv_path *path = iucv_path_table[ips->ippathid];
BUG_ON(!path || !path->handler);
if (!path || !path->handler) /* Already severed */
return;
if (path->handler->path_severed)
path->handler->path_severed(path, ips->ipuser);
else {
iucv_sever_pathid(path->pathid, NULL);
iucv_path_table[path->pathid] = NULL;
list_del_init(&path->list);
iucv_cleanup_pathid(path->pathid);
iucv_path_free(path);
}
}
@ -1309,8 +1332,7 @@ static void iucv_path_quiesced(struct iucv_irq_data *data)
struct iucv_path_quiesced *ipq = (void *) data;
struct iucv_path *path = iucv_path_table[ipq->ippathid];
BUG_ON(!path || !path->handler);
if (path->handler->path_quiesced)
if (path && path->handler && path->handler->path_quiesced)
path->handler->path_quiesced(path, ipq->ipuser);
}
@ -1338,8 +1360,7 @@ static void iucv_path_resumed(struct iucv_irq_data *data)
struct iucv_path_resumed *ipr = (void *) data;
struct iucv_path *path = iucv_path_table[ipr->ippathid];
BUG_ON(!path || !path->handler);
if (path->handler->path_resumed)
if (path && path->handler && path->handler->path_resumed)
path->handler->path_resumed(path, ipr->ipuser);
}
@ -1371,8 +1392,7 @@ static void iucv_message_complete(struct iucv_irq_data *data)
struct iucv_path *path = iucv_path_table[imc->ippathid];
struct iucv_message msg;
BUG_ON(!path || !path->handler);
if (path->handler->message_complete) {
if (path && path->handler && path->handler->message_complete) {
msg.flags = imc->ipflags1;
msg.id = imc->ipmsgid;
msg.audit = imc->ipaudit;
@ -1417,8 +1437,7 @@ static void iucv_message_pending(struct iucv_irq_data *data)
struct iucv_path *path = iucv_path_table[imp->ippathid];
struct iucv_message msg;
BUG_ON(!path || !path->handler);
if (path->handler->message_pending) {
if (path && path->handler && path->handler->message_pending) {
msg.flags = imp->ipflags1;
msg.id = imp->ipmsgid;
msg.class = imp->iptrgcls;
@ -1433,17 +1452,16 @@ static void iucv_message_pending(struct iucv_irq_data *data)
}
/**
* iucv_tasklet_handler:
* iucv_tasklet_fn:
*
* This tasklet loops over the queue of irq buffers created by
* iucv_external_interrupt, calls the appropriate action handler
* and then frees the buffer.
*/
static void iucv_tasklet_handler(unsigned long ignored)
static void iucv_tasklet_fn(unsigned long ignored)
{
typedef void iucv_irq_fn(struct iucv_irq_data *);
static iucv_irq_fn *irq_fn[] = {
[0x01] = iucv_path_pending,
[0x02] = iucv_path_complete,
[0x03] = iucv_path_severed,
[0x04] = iucv_path_quiesced,
@ -1453,38 +1471,70 @@ static void iucv_tasklet_handler(unsigned long ignored)
[0x08] = iucv_message_pending,
[0x09] = iucv_message_pending,
};
struct iucv_work *p;
struct list_head task_queue = LIST_HEAD_INIT(task_queue);
struct iucv_irq_list *p, *n;
/* Serialize tasklet, iucv_path_sever and iucv_path_connect. */
spin_lock(&iucv_table_lock);
iucv_tasklet_cpu = smp_processor_id();
iucv_active_cpu = smp_processor_id();
spin_lock_irq(&iucv_work_lock);
while (!list_empty(&iucv_work_queue)) {
p = list_entry(iucv_work_queue.next, struct iucv_work, list);
spin_lock_irq(&iucv_queue_lock);
list_splice_init(&iucv_task_queue, &task_queue);
spin_unlock_irq(&iucv_queue_lock);
list_for_each_entry_safe(p, n, &task_queue, list) {
list_del_init(&p->list);
spin_unlock_irq(&iucv_work_lock);
irq_fn[p->data.iptype](&p->data);
kfree(p);
spin_lock_irq(&iucv_work_lock);
}
spin_unlock_irq(&iucv_work_lock);
iucv_tasklet_cpu = -1;
iucv_active_cpu = -1;
spin_unlock(&iucv_table_lock);
}
/**
* iucv_work_fn:
*
* This work function loops over the queue of path pending irq blocks
* created by iucv_external_interrupt, calls the appropriate action
* handler and then frees the buffer.
*/
static void iucv_work_fn(struct work_struct *work)
{
typedef void iucv_irq_fn(struct iucv_irq_data *);
struct list_head work_queue = LIST_HEAD_INIT(work_queue);
struct iucv_irq_list *p, *n;
/* Serialize tasklet, iucv_path_sever and iucv_path_connect. */
spin_lock_bh(&iucv_table_lock);
iucv_active_cpu = smp_processor_id();
spin_lock_irq(&iucv_queue_lock);
list_splice_init(&iucv_work_queue, &work_queue);
spin_unlock_irq(&iucv_queue_lock);
iucv_cleanup_queue();
list_for_each_entry_safe(p, n, &work_queue, list) {
list_del_init(&p->list);
iucv_path_pending(&p->data);
kfree(p);
}
iucv_active_cpu = -1;
spin_unlock_bh(&iucv_table_lock);
}
/**
* iucv_external_interrupt
* @code: irq code
*
* Handles external interrupts coming in from CP.
* Places the interrupt buffer on a queue and schedules iucv_tasklet_handler().
* Places the interrupt buffer on a queue and schedules iucv_tasklet_fn().
*/
static void iucv_external_interrupt(u16 code)
{
struct iucv_irq_data *p;
struct iucv_work *work;
struct iucv_irq_list *work;
p = percpu_ptr(iucv_irq_data, smp_processor_id());
if (p->ippathid >= iucv_max_pathid) {
@ -1498,16 +1548,23 @@ static void iucv_external_interrupt(u16 code)
printk(KERN_ERR "iucv_do_int: unknown iucv interrupt\n");
return;
}
work = kmalloc(sizeof(struct iucv_work), GFP_ATOMIC);
work = kmalloc(sizeof(struct iucv_irq_list), GFP_ATOMIC);
if (!work) {
printk(KERN_WARNING "iucv_external_interrupt: out of memory\n");
return;
}
memcpy(&work->data, p, sizeof(work->data));
spin_lock(&iucv_work_lock);
list_add_tail(&work->list, &iucv_work_queue);
spin_unlock(&iucv_work_lock);
tasklet_schedule(&iucv_tasklet);
spin_lock(&iucv_queue_lock);
if (p->iptype == 0x01) {
/* Path pending interrupt. */
list_add_tail(&work->list, &iucv_work_queue);
schedule_work(&iucv_work);
} else {
/* The other interrupts. */
list_add_tail(&work->list, &iucv_task_queue);
tasklet_schedule(&iucv_tasklet);
}
spin_unlock(&iucv_queue_lock);
}
/**
@ -1577,12 +1634,14 @@ out:
*/
static void iucv_exit(void)
{
struct iucv_work *p, *n;
struct iucv_irq_list *p, *n;
spin_lock_irq(&iucv_work_lock);
spin_lock_irq(&iucv_queue_lock);
list_for_each_entry_safe(p, n, &iucv_task_queue, list)
kfree(p);
list_for_each_entry_safe(p, n, &iucv_work_queue, list)
kfree(p);
spin_unlock_irq(&iucv_work_lock);
spin_unlock_irq(&iucv_queue_lock);
unregister_hotcpu_notifier(&iucv_cpu_notifier);
percpu_free(iucv_param);
percpu_free(iucv_irq_data);