Commit 97149140 authored Mar 12, 2014 by Gidon Studinski

msm: ecm_ipa: prevent a deadlock in suspend/resume scenario



Due to changes in IPA_RM, a deadlock is encountered in a suspend/resume
scenario. Replacing netif_wake_queue() with netif_start_queue() in the RM
notification callback fixes the problem.

The problem with netif_wake_queue() is that it starts to transmit packets
immediately, using the current context, which belongs to IPA_RM. In the Tx
function, the network driver calls another IPA_RM API which causes a
deadlock. Using netif_start_queue() will only flag the netdev as able to
transmit. The network stack will start transmitting packets later, from
it's own context.

Change-Id: Ic3d2fb4a660c8842f722ef4cce9344b77f124902
Signed-off-by: Gidon Studinski <gidons@codeaurora.org>

parent 2610ea0c

drivers/net/ethernet/msm/ecm_ipa.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -940,8 +940,8 @@ static void ecm_ipa_rm_notify(void *user_data, enum ipa_rm_event event,
		ECM_IPA_LOG_ENTRY();
		if (event == IPA_RM_RESOURCE_GRANTED &&
		netif_queue_stopped(ecm_ipa_ctx->net)) {
		ECM_IPA_DEBUG("Resource Granted - waking queue\n");
		netif_wake_queue(ecm_ipa_ctx->net);
		ECM_IPA_DEBUG("Resource Granted - starting queue\n");
		netif_start_queue(ecm_ipa_ctx->net);
		} else {
		ECM_IPA_DEBUG("Resource released\n");
		}