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

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>
This commit is contained in:
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
drivers/staging/greybus/operation.c
View File

@ -891,7 +891,7 @@ static void gb_connection_recv_response(struct gb_connection *connection,
size_t message_size;
if (!operation_id) {
dev_err(&connection->hd->dev,
dev_err_ratelimited(&connection->hd->dev,
"%s: invalid response id 0 received\n",
connection->name);
return;
@ -899,9 +899,9 @@ static void gb_connection_recv_response(struct gb_connection *connection,
operation = gb_operation_find_outgoing(connection, operation_id);
if (!operation) {
dev_err(&connection->hd->dev,
"%s: unexpected response id 0x%04x received\n",
connection->name, operation_id);
dev_err_ratelimited(&connection->hd->dev,
"%s: unexpected response id 0x%04x received\n",
connection->name, operation_id);
return;
}
@ -909,7 +909,7 @@ static void gb_connection_recv_response(struct gb_connection *connection,
header = message->header;
message_size = sizeof(*header) + message->payload_size;
if (!errno && size > message_size) {
dev_err(&connection->hd->dev,
dev_err_ratelimited(&connection->hd->dev,
"%s: malformed response 0x%02x received (%zu > %zu)\n",
connection->name, header->type,
size, message_size);
@ -918,7 +918,7 @@ static void gb_connection_recv_response(struct gb_connection *connection,
if (gb_operation_short_response_allowed(operation)) {
message->payload_size = size - sizeof(*header);
} else {
dev_err(&connection->hd->dev,
dev_err_ratelimited(&connection->hd->dev,
"%s: short response 0x%02x received (%zu < %zu)\n",
connection->name, header->type,
size, message_size);
@ -956,13 +956,14 @@ void gb_connection_recv(struct gb_connection *connection,
if ((connection->state != GB_CONNECTION_STATE_ENABLED &&
connection->state != GB_CONNECTION_STATE_ENABLED_TX) ||
gb_connection_is_offloaded(connection)) {
dev_warn(dev, "%s: dropping %zu received bytes\n",
dev_warn_ratelimited(dev, "%s: dropping %zu received bytes\n",
connection->name, size);
return;
}
if (size < sizeof(header)) {
dev_err(dev, "%s: short message received\n", connection->name);
dev_err_ratelimited(dev, "%s: short message received\n",
connection->name);
return;
}
@ -970,10 +971,11 @@ void gb_connection_recv(struct gb_connection *connection,
memcpy(&header, data, sizeof(header));
msg_size = le16_to_cpu(header.size);
if (size < msg_size) {
dev_err(dev,
"%s: incomplete message 0x%04x of type 0x%02x received (%zu < %zu)\n",
connection->name, le16_to_cpu(header.operation_id),
header.type, size, msg_size);
dev_err_ratelimited(dev,
"%s: incomplete message 0x%04x of type 0x%02x received (%zu < %zu)\n",
connection->name,
le16_to_cpu(header.operation_id),
header.type, size, msg_size);
return; /* XXX Should still complete operation */
}