nvme: change namespaces_mutext to namespaces_rwsem

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namespaces_mutext is used to synchronize the operations on ctrl
namespaces list. Most of the time, it is a read operation.

On the other hand, there are many interfaces in nvme core that
need this lock, such as nvme_wait_freeze, and even more interfaces
will be added. If we use mutex here, circular dependency could be
introduced easily. For example:
context A                  context B
nvme_xxx                   nvme_xxx
hold namespaces_mutext     require namespaces_mutext
sync context B

So it is better to change it from mutex to rwsem.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

...

This commit is contained in:

Jianchao Wang 2018-02-12 20:54:46 +08:00 • committed by Jens Axboe

parent 6f8e0d787e

commit 765cc031cd

3 changed files with 35 additions and 35 deletions

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64

drivers/nvme/host/core.c

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4

drivers/nvme/host/multipath.c

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2

drivers/nvme/host/nvme.h

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