linux-kernel - [PATCH v2] media: saa7164: fix remove_proc

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Message-ID: <20190527121455.177296-1-wangkefeng.wang@huawei.com>
Date:   Mon, 27 May 2019 20:14:55 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Kefeng Wang <wangkefeng.wang@...wei.com>,
        Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        "Mauro Carvalho Chehab" <mchehab+samsung@...nel.org>
Subject: [PATCH v2] media: saa7164: fix remove_proc_entry warning

if saa7164_proc_create() fails, saa7164_fini() will trigger a warning,

name 'saa7164'
WARNING: CPU: 1 PID: 6311 at fs/proc/generic.c:672 remove_proc_entry+0x1e8/0x3a0
  ? remove_proc_entry+0x1e8/0x3a0
  ? try_stop_module+0x7b/0x240
  ? proc_readdir+0x70/0x70
  ? rcu_read_lock_sched_held+0xd7/0x100
  saa7164_fini+0x13/0x1f [saa7164]
  __x64_sys_delete_module+0x30c/0x480
  ? __ia32_sys_delete_module+0x480/0x480
  ? __x64_sys_clock_gettime+0x11e/0x1c0
  ? __x64_sys_timer_create+0x1a0/0x1a0
  ? trace_hardirqs_off_caller+0x40/0x180
  ? do_syscall_64+0x18/0x450
  do_syscall_64+0x9f/0x450
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fix it by checking the return of proc_create_single() before
calling remove_proc_entry().

Cc: Hans Verkuil <hverkuil@...all.nl>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 drivers/media/pci/saa7164/saa7164-core.c | 33 ++++++++++++++++--------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/drivers/media/pci/saa7164/saa7164-core.c b/drivers/media/pci/saa7164/saa7164-core.c
index 05f25c9bb308..04d566b1b41e 100644
--- a/drivers/media/pci/saa7164/saa7164-core.c
+++ b/drivers/media/pci/saa7164/saa7164-core.c
@@ -1122,16 +1122,25 @@ static int saa7164_proc_show(struct seq_file *m, void *v)
 	return 0;
 }
 
+static struct proc_dir_entry *saa7164_pe;
+
 static int saa7164_proc_create(void)
 {
-	struct proc_dir_entry *pe;
-
-	pe = proc_create_single("saa7164", S_IRUGO, NULL, saa7164_proc_show);
-	if (!pe)
+	saa7164_pe = proc_create_single("saa7164", S_IRUGO, NULL, saa7164_proc_show);
+	if (!saa7164_pe)
 		return -ENOMEM;
 
 	return 0;
 }
+
+static void saa7164_proc_destroy(void)
+{
+	if (saa7164_pe)
+		remove_proc_entry("saa7164", NULL);
+}
+#else
+static int saa7164_proc_create(void) { return 0; }
+static void saa7164_proc_destroy(void) {}
 #endif
 
 static int saa7164_thread_function(void *data)
@@ -1503,19 +1512,21 @@ static struct pci_driver saa7164_pci_driver = {
 
 static int __init saa7164_init(void)
 {
-	printk(KERN_INFO "saa7164 driver loaded\n");
+	int ret = pci_register_driver(&saa7164_pci_driver);
+
+	if (ret)
+		return ret;
 
-#ifdef CONFIG_PROC_FS
 	saa7164_proc_create();
-#endif
-	return pci_register_driver(&saa7164_pci_driver);
+
+	printk(KERN_INFO "saa7164 driver loaded\n");
+
+	return 0;
 }
 
 static void __exit saa7164_fini(void)
 {
-#ifdef CONFIG_PROC_FS
-	remove_proc_entry("saa7164", NULL);
-#endif
+	saa7164_proc_destroy();
 	pci_unregister_driver(&saa7164_pci_driver);
 }
 
-- 
2.20.1