linux-kernel - [PATCH v7] devcoredump: change gfp_t parameter of kzalloc to GFP

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Date:   Tue, 28 Jun 2022 11:44:58 +0800
From:   Duoming Zhou <duoming@....edu.cn>
To:     linux-kernel@...r.kernel.org
Cc:     rafael@...nel.org, gregkh@...uxfoundation.org,
        johannes@...solutions.net, Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH v7] devcoredump: change gfp_t parameter of kzalloc to GFP_KERNEL

The dev_coredumpv() and dev_coredumpm() could not be used in atomic
context, because they call kvasprintf_const() and kstrdup() with
GFP_KERNEL parameter. The process is shown below:

dev_coredumpv(.., gfp_t gfp)
  dev_coredumpm(.., gfp_t gfp)
    kzalloc(.., gfp);
    dev_set_name
      kobject_set_name_vargs
        kvasprintf_const(GFP_KERNEL, ...); //may sleep
          kstrdup(s, GFP_KERNEL); //may sleep

This patch changes the gfp_t parameter of kzalloc() in dev_coredumpm() to
GFP_KERNEL in order to show they could not be used in atomic context.

What's more, this patch does not remove the gfp_t parameter in
dev_coredumpv() and dev_coredumpm() in order that it will not influence
other new users that are added in other trees.

Fixes: 833c95456a70 ("device coredump: add new device coredump class")
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
Changes in v7:
  - change gfp_t parameter of kzalloc in dev_coredumpm() to GFP_KERNEL.

 drivers/base/devcoredump.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c
index f4d794d6bb8..cf60aacf8a8 100644
--- a/drivers/base/devcoredump.c
+++ b/drivers/base/devcoredump.c
@@ -268,7 +268,7 @@ void dev_coredumpm(struct device *dev, struct module *owner,
 	if (!try_module_get(owner))
 		goto free;
 
-	devcd = kzalloc(sizeof(*devcd), gfp);
+	devcd = kzalloc(sizeof(*devcd), GFP_KERNEL);
 	if (!devcd)
 		goto put_module;
 
-- 
2.17.1