netdev - [PATCH net-next 3/6] net: ipa: track committed transactions with an ID

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Date:   Wed, 31 Aug 2022 17:40:14 -0500
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com
Cc:     mka@...omium.org, evgreen@...omium.org, bjorn.andersson@...aro.org,
        quic_cpratapa@...cinc.com, quic_avuyyuru@...cinc.com,
        quic_jponduru@...cinc.com, quic_subashab@...cinc.com,
        elder@...nel.org, netdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next 3/6] net: ipa: track committed transactions with an ID

Add a transaction ID field to track the first element in a channel's
transaction array that has been committed, but not yet passed to the
hardware.  Advance the ID when the hardware is notified via doorbell
that TREs from a transaction are ready for consumption.

Temporarily add warnings that verify that the first committed
transaction tracked by the ID matches the first element on the
committed list, both when committing and pending (at doorbell).

Remove the temporary warnings added by the previous commit.

Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ipa/gsi.h       |  1 +
 drivers/net/ipa/gsi_trans.c | 45 +++++++++++++++++++++++--------------
 2 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/drivers/net/ipa/gsi.h b/drivers/net/ipa/gsi.h
index 6bbbda6f27eae..cc46a9119fc5b 100644
--- a/drivers/net/ipa/gsi.h
+++ b/drivers/net/ipa/gsi.h
@@ -85,6 +85,7 @@ struct gsi_trans_info {
 
 	u16 free_id;			/* first free trans in array */
 	u16 allocated_id;		/* first allocated transaction */
+	u16 committed_id;		/* first committed transaction */
 	struct gsi_trans *trans;	/* transaction array */
 	struct gsi_trans **map;		/* TRE -> transaction map */
 
diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
index d84400e13487f..72da795908fee 100644
--- a/drivers/net/ipa/gsi_trans.c
+++ b/drivers/net/ipa/gsi_trans.c
@@ -252,20 +252,17 @@ static void gsi_trans_move_committed(struct gsi_trans *trans)
 
 	list_move_tail(&trans->links, &trans_info->committed);
 
-	trans = list_first_entry_or_null(&trans_info->alloc,
-					 struct gsi_trans, links);
+	trans = list_first_entry(&trans_info->committed,
+				 struct gsi_trans, links);
 
 	spin_unlock_bh(&trans_info->spinlock);
 
 	/* This allocated transaction is now committed */
 	trans_info->allocated_id++;
 
-	if (trans) {
-		trans_index = trans_info->allocated_id % channel->tre_count;
-		WARN_ON(trans != &trans_info->trans[trans_index]);
-	} else {
-		WARN_ON(trans_info->allocated_id != trans_info->free_id);
-	}
+	WARN_ON(trans_info->committed_id == trans_info->allocated_id);
+	trans_index = trans_info->committed_id % channel->tre_count;
+	WARN_ON(trans != &trans_info->trans[trans_index]);
 }
 
 /* Move transactions from the committed list to the pending list */
@@ -273,7 +270,9 @@ static void gsi_trans_move_pending(struct gsi_trans *trans)
 {
 	struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
 	struct gsi_trans_info *trans_info = &channel->trans_info;
+	u16 trans_index = trans - &trans_info->trans[0];
 	struct list_head list;
+	u16 delta;
 
 	spin_lock_bh(&trans_info->spinlock);
 
@@ -281,7 +280,22 @@ static void gsi_trans_move_pending(struct gsi_trans *trans)
 	list_cut_position(&list, &trans_info->committed, &trans->links);
 	list_splice_tail(&list, &trans_info->pending);
 
+	trans = list_first_entry_or_null(&trans_info->committed,
+					 struct gsi_trans, links);
+
 	spin_unlock_bh(&trans_info->spinlock);
+
+	/* These committed transactions are now pending */
+	delta = trans_index - trans_info->committed_id + 1;
+	trans_info->committed_id += delta % channel->tre_count;
+
+	if (trans) {
+		trans_index = trans_info->committed_id % channel->tre_count;
+		WARN_ON(trans != &trans_info->trans[trans_index]);
+	} else {
+		WARN_ON(trans_info->committed_id !=
+			trans_info->allocated_id);
+	}
 }
 
 /* Move a transaction and all of its predecessors from the pending list
@@ -392,14 +406,8 @@ struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
 
 	list_add_tail(&trans->links, &trans_info->alloc);
 
-	trans = list_first_entry(&trans_info->alloc, struct gsi_trans, links);
-
 	spin_unlock_bh(&trans_info->spinlock);
 
-	WARN_ON(trans_info->allocated_id == trans_info->free_id);
-	trans_index = trans_info->allocated_id % channel->tre_count;
-	WARN_ON(trans != &trans_info->trans[trans_index]);
-
 	return trans;
 }
 
@@ -428,11 +436,13 @@ void gsi_trans_free(struct gsi_trans *trans)
 	if (!last)
 		return;
 
-	/* Unused transactions are allocated but never committed */
-	if (!trans->used_count)
+	/* Unused transactions are allocated but never committed or pending */
+	if (!trans->used_count) {
 		trans_info->allocated_id++;
-	else
+		trans_info->committed_id++;
+	} else {
 		ipa_gsi_trans_release(trans);
+	}
 
 	/* Releasing the reserved TREs implicitly frees the sgl[] and
 	 * (if present) info[] arrays, plus the transaction itself.
@@ -769,6 +779,7 @@ int gsi_channel_trans_init(struct gsi *gsi, u32 channel_id)
 		return -ENOMEM;
 	trans_info->free_id = 0;	/* all modulo channel->tre_count */
 	trans_info->allocated_id = 0;
+	trans_info->committed_id = 0;
 
 	/* A completion event contains a pointer to the TRE that caused
 	 * the event (which will be the last one used by the transaction).
-- 
2.34.1