[openib-general] RFC: deadlock in uverbs_cmd.c

[Michael S. Tsirkin]

Quoting r. Roland Dreier <rdreier at cisco.com>:
> Subject: Re: RFC: deadlock in uverbs_cmd.c
> 
>     Michael> Hello!  uverbs_cmd currently locks both send and receive
>     Michael> cq with down_write during ib_uverbs_create_qp operation.
> 
> It does?  It seems that the code in question is:
> 
> 	scq = idr_read_cq(cmd.send_cq_handle, file->ucontext);
> 	rcq = idr_read_cq(cmd.recv_cq_handle, file->ucontext);
> 
> which should use down_read() and be safe.

Bzzt. Sorry.

>     Michael> Comments?  Further, Roland, would you mind writing up
>     Michael> something about the lock nesting in uverbs?
> 
> OK, I'll add that to my todo list.
> 
>  - R.
> 

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