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net: ipa: prevent concurrent replenish
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We have seen cases where an endpoint RX completion interrupt arrives
while replenishing for the endpoint is underway.  This causes another
instance of replenishing to begin as part of completing the receive
transaction.  If this occurs it can lead to transaction corruption.

Use a new flag to ensure only one replenish instance for an endpoint
executes at a time.

Fixes: 84f9bd1 ("soc: qcom: ipa: IPA endpoints")
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Alex Elder authored and davem330 committed Jan 12, 2022
1 parent c1aaa01 commit 998c0bd
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Showing 2 changed files with 15 additions and 0 deletions.
13 changes: 13 additions & 0 deletions drivers/net/ipa/ipa_endpoint.c
Original file line number Diff line number Diff line change
Expand Up @@ -1088,15 +1088,27 @@ static void ipa_endpoint_replenish(struct ipa_endpoint *endpoint, bool add_one)
return;
}

/* If already active, just update the backlog */
if (test_and_set_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags)) {
if (add_one)
atomic_inc(&endpoint->replenish_backlog);
return;
}

while (atomic_dec_not_zero(&endpoint->replenish_backlog))
if (ipa_endpoint_replenish_one(endpoint))
goto try_again_later;

clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);

if (add_one)
atomic_inc(&endpoint->replenish_backlog);

return;

try_again_later:
clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);

/* The last one didn't succeed, so fix the backlog */
delta = add_one ? 2 : 1;
backlog = atomic_add_return(delta, &endpoint->replenish_backlog);
Expand Down Expand Up @@ -1691,6 +1703,7 @@ static void ipa_endpoint_setup_one(struct ipa_endpoint *endpoint)
* backlog is the same as the maximum outstanding TREs.
*/
clear_bit(IPA_REPLENISH_ENABLED, endpoint->replenish_flags);
clear_bit(IPA_REPLENISH_ACTIVE, endpoint->replenish_flags);
atomic_set(&endpoint->replenish_saved,
gsi_channel_tre_max(gsi, endpoint->channel_id));
atomic_set(&endpoint->replenish_backlog, 0);
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2 changes: 2 additions & 0 deletions drivers/net/ipa/ipa_endpoint.h
Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,12 @@ enum ipa_endpoint_name {
* enum ipa_replenish_flag: RX buffer replenish flags
*
* @IPA_REPLENISH_ENABLED: Whether receive buffer replenishing is enabled
* @IPA_REPLENISH_ACTIVE: Whether replenishing is underway
* @IPA_REPLENISH_COUNT: Number of defined replenish flags
*/
enum ipa_replenish_flag {
IPA_REPLENISH_ENABLED,
IPA_REPLENISH_ACTIVE,
IPA_REPLENISH_COUNT, /* Number of flags (must be last) */
};

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