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| author |   Parav Pandit <parav@mellanox.com> | 2019-10-15 11:07:33 +0300 |
|---|---|---|
| committer |   Jason Gunthorpe <jgg@mellanox.com> | 2019-10-24 20:49:37 -0300 |
| commit | 549af00833028b5803528553a4743e0cd1fdbee9 (patch) | |
| tree | 3c46d34374cbcb9d796fe4ce914015350fe756ea /drivers/infiniband/core/core_priv.h | |
| parent | RDMA/nldev: Skip counter if port doesn't match (diff) | |
| download | linux-dev-549af00833028b5803528553a4743e0cd1fdbee9.tar.xz linux-dev-549af00833028b5803528553a4743e0cd1fdbee9.zip | |
IB/core: Avoid deadlock during netlink message handling
When rdmacm module is not loaded, and when netlink message is received to
get char device info, it results into a deadlock due to recursive locking
of rdma_nl_mutex with the below call sequence.
[..]
rdma_nl_rcv()
mutex_lock()
[..]
rdma_nl_rcv_msg()
ib_get_client_nl_info()
request_module()
iw_cm_init()
rdma_nl_register()
mutex_lock(); <- Deadlock, acquiring mutex again
Due to above call sequence, following call trace and deadlock is observed.
kernel: __mutex_lock+0x35e/0x860
kernel: ? __mutex_lock+0x129/0x860
kernel: ? rdma_nl_register+0x1a/0x90 [ib_core]
kernel: rdma_nl_register+0x1a/0x90 [ib_core]
kernel: ? 0xffffffffc029b000
kernel: iw_cm_init+0x34/0x1000 [iw_cm]
kernel: do_one_initcall+0x67/0x2d4
kernel: ? kmem_cache_alloc_trace+0x1ec/0x2a0
kernel: do_init_module+0x5a/0x223
kernel: load_module+0x1998/0x1e10
kernel: ? __symbol_put+0x60/0x60
kernel: __do_sys_finit_module+0x94/0xe0
kernel: do_syscall_64+0x5a/0x270
kernel: entry_SYSCALL_64_after_hwframe+0x49/0xbe
process stack trace:
[<0>] __request_module+0x1c9/0x460
[<0>] ib_get_client_nl_info+0x5e/0xb0 [ib_core]
[<0>] nldev_get_chardev+0x1ac/0x320 [ib_core]
[<0>] rdma_nl_rcv_msg+0xeb/0x1d0 [ib_core]
[<0>] rdma_nl_rcv+0xcd/0x120 [ib_core]
[<0>] netlink_unicast+0x179/0x220
[<0>] netlink_sendmsg+0x2f6/0x3f0
[<0>] sock_sendmsg+0x30/0x40
[<0>] ___sys_sendmsg+0x27a/0x290
[<0>] __sys_sendmsg+0x58/0xa0
[<0>] do_syscall_64+0x5a/0x270
[<0>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
To overcome this deadlock and to allow multiple netlink messages to
progress in parallel, following scheme is implemented.
1. Split the lock protecting the cb_table into a per-index lock, and make
it a rwlock. This lock is used to ensure no callbacks are running after
unregistration returns. Since a module will not be registered once it
is already running callbacks, this avoids the deadlock.
2. Use smp_store_release() to update the cb_table during registration so
that no lock is required. This avoids lockdep problems with thinking
all the rwsems are the same lock class.
Fixes: 0e2d00eb6fd45 ("RDMA: Add NLDEV_GET_CHARDEV to allow char dev discovery and autoload")
Link: https://lore.kernel.org/r/20191015080733.18625-1-leon@kernel.org
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to '')
| -rw-r--r-- | drivers/infiniband/core/core_priv.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/infiniband/core/core_priv.h b/drivers/infiniband/core/core_priv.h index 3a8b0911c3bc..9d07378b5b42 100644 --- a/drivers/infiniband/core/core_priv.h +++ b/drivers/infiniband/core/core_priv.h @@ -199,6 +199,7 @@ void ib_mad_cleanup(void); int ib_sa_init(void); void ib_sa_cleanup(void); +void rdma_nl_init(void); void rdma_nl_exit(void); int ib_nl_handle_resolve_resp(struct sk_buff *skb, |