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authorStefan Weinhuber <wein@de.ibm.com>2008-02-19 15:29:27 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2008-02-19 15:29:33 +0100
commit03513bccad33667ed738cfd96dc5757e539e0bdb (patch)
treefd6d91ac38deb371bb29b567894056a8c8f9e4e0 /drivers
parent11ab244c9faead91683a12e4cb10d26b279bb4aa (diff)
downloadop-kernel-dev-03513bccad33667ed738cfd96dc5757e539e0bdb.zip
op-kernel-dev-03513bccad33667ed738cfd96dc5757e539e0bdb.tar.gz
[S390] dasd: fix locking in __dasd_device_process_final_queue
After setting the status of the cqr and releasing the lock for the block cqr queue, we call the cqr callback function, which will usually just trigger the dasd_block_tasklet. But when the tasklet is already running the cqr might be processed before we invoke the callback function. In rare cases the callback pointer may already be invalid by the time we want to call it, which will result in a panic. Solution: Call the callback function first and then release the lock. Signed-off-by: Stefan Weinhuber <wein@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/s390/block/dasd.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index d984e0f..ccf46c9 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1149,12 +1149,14 @@ static void __dasd_device_process_final_queue(struct dasd_device *device,
{
struct list_head *l, *n;
struct dasd_ccw_req *cqr;
+ struct dasd_block *block;
list_for_each_safe(l, n, final_queue) {
cqr = list_entry(l, struct dasd_ccw_req, devlist);
list_del_init(&cqr->devlist);
- if (cqr->block)
- spin_lock_bh(&cqr->block->queue_lock);
+ block = cqr->block;
+ if (block)
+ spin_lock_bh(&block->queue_lock);
switch (cqr->status) {
case DASD_CQR_SUCCESS:
cqr->status = DASD_CQR_DONE;
@@ -1172,15 +1174,13 @@ static void __dasd_device_process_final_queue(struct dasd_device *device,
cqr, cqr->status);
BUG();
}
- if (cqr->block)
- spin_unlock_bh(&cqr->block->queue_lock);
if (cqr->callback != NULL)
(cqr->callback)(cqr, cqr->callback_data);
+ if (block)
+ spin_unlock_bh(&block->queue_lock);
}
}
-
-
/*
* Take a look at the first request on the ccw queue and check
* if it reached its expire time. If so, terminate the IO.
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