linux-kernel - [PATCH] firewire: core: revert GFP

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Message-ID: <89fe5e6f-d6c3-42d6-bf86-3eb1f4193c1b@kili.mountain>
Date:   Mon, 17 Jul 2023 12:50:20 +0300
From:   Dan Carpenter <dan.carpenter@...aro.org>
To:     Takashi Sakamoto <o-takashi@...amocchi.jp>
Cc:     linux1394-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] firewire: core: revert GFP_ATOMIC changes

This was recently changed from GFP_ATOMIC to GFP_KERNEL, but Smatch
complains that GFP_ATOMIC is still required:

drivers/firewire/core-topology.c:223 build_tree() warn: sleeping in atomic context

The problematic call trees are:

fw_core_handle_bus_reset() <- spin_lock_irqsave(&card->lock, flags);
-> build_tree()
   -> fw_node_create() <- sleeping allocation

fw_core_handle_bus_reset() <- spin_lock_irqsave(&card->lock, flags);
-> update_tree()
   -> fw_node_event()

This second call tree is a bit complicated because we event is not
FW_NODE_CREATED so we would have to hit a goto create; to hit the
bug.

Fixes: 06f45435d985 ("firewire: core: obsolete usage of GFP_ATOMIC at building node tree")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
>From static analysis.  Smatch does not warn about fw_node_event()
because event can't be FW_NODE_CREATED.

 drivers/firewire/core-device.c   | 2 +-
 drivers/firewire/core-topology.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index a3104e35412c..aa597cda0d88 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -1211,7 +1211,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 		 * without actually having a link.
 		 */
  create:
-		device = kzalloc(sizeof(*device), GFP_KERNEL);
+		device = kzalloc(sizeof(*device), GFP_ATOMIC);
 		if (device == NULL)
 			break;
 
diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core-topology.c
index 88466b663482..f40c81534381 100644
--- a/drivers/firewire/core-topology.c
+++ b/drivers/firewire/core-topology.c
@@ -101,7 +101,7 @@ static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
 {
 	struct fw_node *node;
 
-	node = kzalloc(struct_size(node, ports, port_count), GFP_KERNEL);
+	node = kzalloc(struct_size(node, ports, port_count), GFP_ATOMIC);
 	if (node == NULL)
 		return NULL;
 
-- 
2.39.2