linux-kernel - [PATCH net-next 2/5] net: ipa: kill the allocated transaction list

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Date:   Tue,  6 Sep 2022 12:19:39 -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 2/5] net: ipa: kill the allocated transaction list

The only place the trans_info->alloc list is used is when
initializing it, when adding a transaction to it when allocation
finishes, and when moving a transaction from that list to the
committed list.

We can just skip putting a transaction on the allocated list, and
add it (rather than move it) to the committed list when it is
committed.

On additional caveat is that an allocated transaction that's
committed without any TREs added will be immediately freed.  Because
we aren't adding allocated transactions to a list any more, the
list links need to be initialized to ensure they're valid at the
time list_del() is called for the transaction.

Then we can safely eliminate the allocated transaction list.

Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ipa/gsi.h       |  1 -
 drivers/net/ipa/gsi_trans.c | 12 +++---------
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ipa/gsi.h b/drivers/net/ipa/gsi.h
index 13468704c4000..a3f2d27a7e4b3 100644
--- a/drivers/net/ipa/gsi.h
+++ b/drivers/net/ipa/gsi.h
@@ -96,7 +96,6 @@ struct gsi_trans_info {
 	struct gsi_trans_pool cmd_pool;	/* command payload DMA pool */
 
 	spinlock_t spinlock;		/* protects updates to the lists */
-	struct list_head alloc;		/* allocated, not committed */
 	struct list_head committed;	/* committed, awaiting doorbell */
 	struct list_head pending;	/* pending, awaiting completion */
 	struct list_head complete;	/* completed, awaiting poll */
diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
index a131a4fbb53fc..254c09824004c 100644
--- a/drivers/net/ipa/gsi_trans.c
+++ b/drivers/net/ipa/gsi_trans.c
@@ -246,7 +246,7 @@ struct gsi_trans *gsi_channel_trans_complete(struct gsi_channel *channel)
 	return &trans_info->trans[trans_id %= channel->tre_count];
 }
 
-/* Move a transaction from the allocated list to the committed list */
+/* Move a transaction from allocated to committed state */
 static void gsi_trans_move_committed(struct gsi_trans *trans)
 {
 	struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
@@ -254,7 +254,7 @@ static void gsi_trans_move_committed(struct gsi_trans *trans)
 
 	spin_lock_bh(&trans_info->spinlock);
 
-	list_move_tail(&trans->links, &trans_info->committed);
+	list_add_tail(&trans->links, &trans_info->committed);
 
 	spin_unlock_bh(&trans_info->spinlock);
 
@@ -383,6 +383,7 @@ struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
 	memset(trans, 0, sizeof(*trans));
 
 	/* Initialize non-zero fields in the transaction */
+	INIT_LIST_HEAD(&trans->links);
 	trans->gsi = gsi;
 	trans->channel_id = channel_id;
 	trans->rsvd_count = tre_count;
@@ -398,12 +399,6 @@ struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
 	/* This free transaction will now be allocated */
 	trans_info->free_id++;
 
-	spin_lock_bh(&trans_info->spinlock);
-
-	list_add_tail(&trans->links, &trans_info->alloc);
-
-	spin_unlock_bh(&trans_info->spinlock);
-
 	return trans;
 }
 
@@ -821,7 +816,6 @@ int gsi_channel_trans_init(struct gsi *gsi, u32 channel_id)
 		goto err_map_free;
 
 	spin_lock_init(&trans_info->spinlock);
-	INIT_LIST_HEAD(&trans_info->alloc);
 	INIT_LIST_HEAD(&trans_info->committed);
 	INIT_LIST_HEAD(&trans_info->pending);
 	INIT_LIST_HEAD(&trans_info->complete);
-- 
2.34.1