IB/mad: Use IDR for agent IDs

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Allocate agent IDs from a global IDR instead of an atomic variable.
This eliminates the possibility of reusing an ID which is already in
use after 4 billion registrations.  We limit the assigned ID to be less
than 2^24 as the mlx4 driver uses the most significant byte of the agent
ID to store the slave number.  Users unlucky enough to see a collision
between agent numbers and slave numbers see messages like:

 mlx4_ib: egress mad has non-null tid msb:1 class:4 slave:0

and the MAD layer stops working.

We look up the agent under protection of the RCU lock, which means we
have to free the agent using kfree_rcu, and only increment the reference
counter if it is not 0.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reported-by: Hans Westgaard Ry <hans.westgaard.ry@oracle.com>
Acked-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Tested-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

...

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willy@infradead.org 2018-06-13 05:34:03 -07:00 • committed by Jason Gunthorpe

parent 3c60e868c3

commit 9a41e38a46

2 changed files with 55 additions and 35 deletions

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83

drivers/infiniband/core/mad.c

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7

drivers/infiniband/core/mad_priv.h

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