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Commit 088d0917 authored by Atish Kumar Patra's avatar Atish Kumar Patra Committed by Matt Wagantall
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soc: qcom: glink: Fix race condition for dummy transport deletion 



In ssr/unregister_transport scenario, remote disconnect is faked
to all clients and the channels are moved to a dummy transport
to be closed in future. The dummy transport is deleted once all
the channels on it are fully closed. This may lead to a race
condition where the dummy transport can be deleted while some
channels are still being moved to it.

Fix the race condition by first moving the channels to dummy
transport together and fake remote disconnect to the clients
one by one so that dummy transport will be deleted only
after all the channels are closed.

Change-Id: I0a8e78e562594751b2984f4df4d6030c5abb5d41
Signed-off-by: default avatarAtish Kumar Patra <apatra@codeaurora.org>
parent 5fd84676

drivers/soc/qcom/glink.c

+45 −36
Original line number Diff line number Diff line
@@ -2050,13 +2050,17 @@ int glink_close(void *handle) 
				ctx->transport_ptr->ops,

				ctx->lcid);

	} else if (!strcmp(ctx->transport_ptr->name, "dummy")) {

		/* This case should appear only in case dummy transports */

		/*

		 * This check will avoid any race condition when clients call

		 * glink_close before the dummy xprt swapping happens in link

		 * down scenario.

		 */

		ret = 0;

		xprt_ctx = ctx->transport_ptr;

		rwref_write_get(&xprt_ctx->xprt_state_lhb0);

		glink_core_ch_close_ack_common(ctx);

		if (ch_is_fully_closed(ctx)) {

			xprt_ctx = ctx->transport_ptr;

			glink_delete_ch_from_list(ctx, false);

			/* For each channel reference in the dummy transport */

			rwref_put(&xprt_ctx->xprt_state_lhb0);

			if (list_empty(&xprt_ctx->channels))

				/* For the xprt reference */
@@ -2066,6 +2070,7 @@ int glink_close(void *handle) 
			"channel Not closed yet local state [%d] remote_state [%d]\n",

			ctx->local_open_state, ctx->remote_opened);

		}

		rwref_write_put(&xprt_ctx->xprt_state_lhb0);

	}



	return ret;
@@ -2891,43 +2896,34 @@ static void glink_core_channel_cleanup(struct glink_core_xprt_ctx *xprt_ptr) 
		return;

	}



	rwref_get(&dummy_xprt_ctx->xprt_state_lhb0);

	spin_lock_irqsave(&xprt_ptr->xprt_ctx_lock_lhb1, flags);

	list_for_each_entry_safe(ctx, tmp_ctx, &xprt_ptr->channels,

						port_list_node) {

		if (!ch_is_fully_closed(ctx)) {

		rwref_get(&ctx->ch_state_lhc0);

			if (ctx->local_open_state == GLINK_CHANNEL_CLOSED ||

				ctx->local_open_state ==

						GLINK_CHANNEL_CLOSING) {

				spin_unlock_irqrestore(

					&xprt_ptr->xprt_ctx_lock_lhb1, flags);

				glink_core_remote_close_common(ctx);

				if (ctx->local_open_state ==

						GLINK_CHANNEL_CLOSING)

					glink_core_ch_close_ack_common(ctx);

				/* Channel is fully closed. Delete here */

				if (ch_is_fully_closed(ctx))

					glink_delete_ch_from_list(ctx, false);

			} else {

		if (ctx->local_open_state == GLINK_CHANNEL_OPENED ||

			ctx->local_open_state == GLINK_CHANNEL_OPENING) {

			rwref_get(&dummy_xprt_ctx->xprt_state_lhb0);

				spin_lock_irqsave(

					&dummy_xprt_ctx->xprt_ctx_lock_lhb1,

			spin_lock_irqsave(&dummy_xprt_ctx->xprt_ctx_lock_lhb1,

						d_flags);

			list_move_tail(&ctx->port_list_node,

					&dummy_xprt_ctx->channels);

			spin_unlock_irqrestore(

					&dummy_xprt_ctx->xprt_ctx_lock_lhb1,

					d_flags);

				spin_unlock_irqrestore(

					&xprt_ptr->xprt_ctx_lock_lhb1, flags);

				glink_add_free_lcid_list(ctx);

				&dummy_xprt_ctx->xprt_ctx_lock_lhb1, d_flags);

			ctx->transport_ptr = dummy_xprt_ctx;

		} else {

			/* local state is in either CLOSED or CLOSING */

			spin_unlock_irqrestore(&xprt_ptr->xprt_ctx_lock_lhb1,

							flags);

			glink_core_remote_close_common(ctx);

			if (ctx->local_open_state == GLINK_CHANNEL_CLOSING)

				glink_core_ch_close_ack_common(ctx);

			/* Channel should be fully closed now. Delete here */

			if (ch_is_fully_closed(ctx))

				glink_delete_ch_from_list(ctx, false);

			spin_lock_irqsave(&xprt_ptr->xprt_ctx_lock_lhb1, flags);

		}

		rwref_put(&ctx->ch_state_lhc0);

			spin_lock_irqsave(

				&xprt_ptr->xprt_ctx_lock_lhb1, flags);

		}

	}

	list_for_each_entry_safe(temp_lcid, temp_lcid1,

			&xprt_ptr->free_lcid_list, list_node) {
@@ -2936,6 +2932,19 @@ static void glink_core_channel_cleanup(struct glink_core_xprt_ctx *xprt_ptr) 
	}

	spin_unlock_irqrestore(&xprt_ptr->xprt_ctx_lock_lhb1, flags);



	spin_lock_irqsave(&dummy_xprt_ctx->xprt_ctx_lock_lhb1, d_flags);

	list_for_each_entry_safe(ctx, tmp_ctx, &dummy_xprt_ctx->channels,

						port_list_node) {

		rwref_get(&ctx->ch_state_lhc0);

		spin_unlock_irqrestore(&dummy_xprt_ctx->xprt_ctx_lock_lhb1,

				d_flags);

		glink_core_remote_close_common(ctx);

		spin_lock_irqsave(&dummy_xprt_ctx->xprt_ctx_lock_lhb1,

				d_flags);

		rwref_put(&ctx->ch_state_lhc0);

	}

	spin_unlock_irqrestore(&dummy_xprt_ctx->xprt_ctx_lock_lhb1, d_flags);

	rwref_put(&dummy_xprt_ctx->xprt_state_lhb0);

}

/**

 * glink_core_rx_cmd_version() - receive version/features from remote system