greybus: operation: rate-limit dev_err printing on the receive path

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When we receive Greybus operations we don't recognize, requests or responses,
en masse, we can pile up a lot of dev_err() printk messages.  Doing so along
the gb_connection_recv() code path can delay receive processing by up to seven
milliseconds, starving the system of bulk-IN urbs.  Rate limit those printk
messages, ensuring that after too many repeated errors at the same place in
the code-path, we'll stop printing to the console at all and let the urbs get
returned.

This will help prevent denial-of-service attacks on the AP through the UniPro
network from malicious or malfunctioning modules.

Testing Done: 7 msec recv-to-resubmit-urb processing times go down to <20
usecs

Signed-off-by: Eli Sennesh <esennesh@leaflabs.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Mitchell Tasman <tasman@leaflabs.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

...

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Eli Sennesh 2016-05-13 13:27:40 -04:00 • committed by Greg Kroah-Hartman

parent 3a238fc784

commit b0e97bce15

1 changed files with 14 additions and 12 deletions

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drivers/staging/greybus/operation.c

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