proc 2/2: remove struct proc_dir_entry::owner

Setting ->owner as done currently (pde->owner = THIS_MODULE) is racy
as correctly noted at bug #12454. Someone can lookup entry with NULL
->owner, thus not pinning enything, and release it later resulting
in module refcount underflow.

We can keep ->owner and supply it at registration time like ->proc_fops
and ->data.

But this leaves ->owner as easy-manipulative field (just one C assignment)
and somebody will forget to unpin previous/pin current module when
switching ->owner. ->proc_fops is declared as "const" which should give
some thoughts.

->read_proc/->write_proc were just fixed to not require ->owner for
protection.

rmmod'ed directories will be empty and return "." and ".." -- no harm.
And directories with tricky enough readdir and lookup shouldn't be modular.
We definitely don't want such modular code.

Removing ->owner will also make PDE smaller.

So, let's nuke it.

Kudos to Jeff Layton for reminding about this, let's say, oversight.

http://bugzilla.kernel.org/show_bug.cgi?id=12454

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

8 files changed, 0 insertions, 17 deletions

diff --git a/drivers/acpi/ac.c b/drivers/acpi/ac.c
index 9b917dac773..88e42abf5d8 100644
--- a/drivers/acpi/ac.c
+++ b/drivers/acpi/ac.c
@@ -191,7 +191,6 @@ static int acpi_ac_add_fs(struct acpi_device *device)
 						     acpi_ac_dir);
 		if (!acpi_device_dir(device))
 			return -ENODEV;
-		acpi_device_dir(device)->owner = THIS_MODULE;
 	}
 
 	/* 'state' [R] */
diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 69cbc57c2d1..3bcb5bfc45d 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -760,7 +760,6 @@ static int acpi_battery_add_fs(struct acpi_device *device)
 						     acpi_battery_dir);
 		if (!acpi_device_dir(device))
 			return -ENODEV;
-		acpi_device_dir(device)->owner = THIS_MODULE;
 	}
 
 	for (i = 0; i < ACPI_BATTERY_NUMFILES; ++i) {
diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
index 171fd914f43..c2f06069dcd 100644
--- a/drivers/acpi/button.c
+++ b/drivers/acpi/button.c
@@ -200,12 +200,10 @@ static int acpi_button_add_fs(struct acpi_device *device)
 
 	if (!entry)
 		return -ENODEV;
-	entry->owner = THIS_MODULE;
 
 	acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), entry);
 	if (!acpi_device_dir(device))
 		return -ENODEV;
-	acpi_device_dir(device)->owner = THIS_MODULE;
 
 	/* 'info' [R] */
 	entry = proc_create_data(ACPI_BUTTON_FILE_INFO,
@@ -522,7 +520,6 @@ static int __init acpi_button_init(void)
 	acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
 	if (!acpi_button_dir)
 		return -ENODEV;
-	acpi_button_dir->owner = THIS_MODULE;
 	result = acpi_bus_register_driver(&acpi_button_driver);
 	if (result < 0) {
 		remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
diff --git a/drivers/acpi/fan.c b/drivers/acpi/fan.c
index eaaee1660bd..8a02944bf92 100644
--- a/drivers/acpi/fan.c
+++ b/drivers/acpi/fan.c
@@ -193,7 +193,6 @@ static int acpi_fan_add_fs(struct acpi_device *device)
 						     acpi_fan_dir);
 		if (!acpi_device_dir(device))
 			return -ENODEV;
-		acpi_device_dir(device)->owner = THIS_MODULE;
 	}
 
 	/* 'status' [R/W] */
@@ -347,7 +346,6 @@ static int __init acpi_fan_init(void)
 	acpi_fan_dir = proc_mkdir(ACPI_FAN_CLASS, acpi_root_dir);
 	if (!acpi_fan_dir)
 		return -ENODEV;
-	acpi_fan_dir->owner = THIS_MODULE;
 #endif
 
 	result = acpi_bus_register_driver(&acpi_fan_driver);
diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 0cc2fd31e37..fa2f7422d23 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -359,7 +359,6 @@ static int acpi_processor_add_fs(struct acpi_device *device)
 		if (!acpi_device_dir(device))
 			return -ENODEV;
 	}
-	acpi_device_dir(device)->owner = THIS_MODULE;
 
 	/* 'info' [R] */
 	entry = proc_create_data(ACPI_PROCESSOR_FILE_INFO,
@@ -1137,7 +1136,6 @@ static int __init acpi_processor_init(void)
 	acpi_processor_dir = proc_mkdir(ACPI_PROCESSOR_CLASS, acpi_root_dir);
 	if (!acpi_processor_dir)
 		return -ENOMEM;
-	acpi_processor_dir->owner = THIS_MODULE;
 
 	/*
 	 * Check whether the system is DMI table. If yes, OSPM
diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index 6050ce48187..59afd52ccc1 100644
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -488,7 +488,6 @@ acpi_sbs_add_fs(struct proc_dir_entry **dir,
 		if (!*dir) {
 			return -ENODEV;
 		}
-		(*dir)->owner = THIS_MODULE;
 	}
 
 	/* 'info' [R] */
diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index 99e6f1f8ea4..c11f9aeca70 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -1506,7 +1506,6 @@ static int acpi_thermal_add_fs(struct acpi_device *device)
 						     acpi_thermal_dir);
 		if (!acpi_device_dir(device))
 			return -ENODEV;
-		acpi_device_dir(device)->owner = THIS_MODULE;
 	}
 
 	/* 'state' [R] */
@@ -1875,7 +1874,6 @@ static int __init acpi_thermal_init(void)
 	acpi_thermal_dir = proc_mkdir(ACPI_THERMAL_CLASS, acpi_root_dir);
 	if (!acpi_thermal_dir)
 		return -ENODEV;
-	acpi_thermal_dir->owner = THIS_MODULE;
 
 	result = acpi_bus_register_driver(&acpi_thermal_driver);
 	if (result < 0) {
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index bb5ed059114..67cc36dc9b8 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -1125,8 +1125,6 @@ static int acpi_video_device_add_fs(struct acpi_device *device)
 	if (!device_dir)
 		return -ENOMEM;
 
-	device_dir->owner = THIS_MODULE;
-
 	/* 'info' [R] */
 	entry = proc_create_data("info", S_IRUGO, device_dir,
 			&acpi_video_device_info_fops, acpi_driver_data(device));
@@ -1403,8 +1401,6 @@ static int acpi_video_bus_add_fs(struct acpi_device *device)
 	if (!device_dir)
 		return -ENOMEM;
 
-	device_dir->owner = THIS_MODULE;
-
 	/* 'info' [R] */
 	entry = proc_create_data("info", S_IRUGO, device_dir,
 				 &acpi_video_bus_info_fops,
@@ -2131,7 +2127,6 @@ static int __init acpi_video_init(void)
 	acpi_video_dir = proc_mkdir(ACPI_VIDEO_CLASS, acpi_root_dir);
 	if (!acpi_video_dir)
 		return -ENODEV;
-	acpi_video_dir->owner = THIS_MODULE;
 
 	result = acpi_bus_register_driver(&acpi_video_bus);
 	if (result < 0) {