cxgb4: Synchronize access to mailbox

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The issue comes when there are multiple threads attempting to use
the mailbox facility at the same time.
When DCB operations and interface up/down is run in a loop for every
0.1 sec, we observed mailbox collisions. And out of the two commands
one would fail with the present code, since we don't queue the second
command.

To overcome the above issue, added a queue to access the mailbox.
Whenever a mailbox command is issued add it to the queue. If its at
the head issue the mailbox command, else wait for the existing command
to complete. Usually command takes less than a milli-second to
complete.

Also timeout from the loop, if the command under execution takes
long time to run.

In reality, the number of mailbox access collisions is going to be
very rare since no one runs such abusive script.

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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This commit is contained in:

Hariprasad Shenai 2017-01-06 08:47:20 +05:30 • committed by David S. Miller

parent 4b92ea81cc

commit 4055ae5e6d

3 changed files with 69 additions and 1 deletions

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8

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

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3

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

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59

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

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