Use of rcu_read_lock solves this problem. Rcu_read_lock and spinlock on same data can
Co-exist at the same time. That is the whole point. All this is going away soon.
Bob
-----Original Message-----
From: yanjun.zhu@xxxxxxxxx <yanjun.zhu@xxxxxxxxx>
Sent: Friday, April 22, 2022 2:44 PM
To: jgg@xxxxxxxx; leon@xxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; yanjun.zhu@xxxxxxxxx
Cc: Yi Zhang <yi.zhang@xxxxxxxxxx>
Subject: [PATCHv6 1/4] RDMA/rxe: Fix dead lock caused by __rxe_add_to_pool interrupted by rxe_pool_get_index
From: Zhu Yanjun <yanjun.zhu@xxxxxxxxx>
This is a dead lock problem.
The ah_pool xa_lock first is acquired in this:
{SOFTIRQ-ON-W} state was registered at:
lock_acquire+0x1d2/0x5a0
_raw_spin_lock+0x33/0x80
__rxe_add_to_pool+0x183/0x230 [rdma_rxe]
Then ah_pool xa_lock is acquired in this:
{IN-SOFTIRQ-W}:
Call Trace:
<TASK>
dump_stack_lvl+0x44/0x57
mark_lock.part.52.cold.79+0x3c/0x46
__lock_acquire+0x1565/0x34a0
lock_acquire+0x1d2/0x5a0
_raw_spin_lock_irqsave+0x42/0x90
rxe_pool_get_index+0x72/0x1d0 [rdma_rxe]
rxe_get_av+0x168/0x2a0 [rdma_rxe]
</TASK>
