[PATCH -mm 0/2] swsusp: Use GFP_KERNEL for creating basic data structures

[PATCH -mm 0/2] swsusp: Use GFP_KERNEL for creating basic data structures

[Rafael J. Wysocki]

Hi,

The first of the following two patches fixes a bug in the swsusp's userland
interface and the second one makes swsusp use GFP_KERNEL allocations for
creating its basic memory bitmaps.

Greetings,
Rafael

[PATCH -mm 1/2] swsusp: Fix error paths in snapshot_open

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

We forget to increase device_available if there's an error in snapshot_open(),
so the snapshot device cannot be open at all after snapshot_open() has returned
an error.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 kernel/power/user.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: linux-2.6.21-rc4/kernel/power/user.c
===================================================================
--- linux-2.6.21-rc4.orig/kernel/power/user.c
+++ linux-2.6.21-rc4/kernel/power/user.c
@@ -49,12 +49,14 @@ static int snapshot_open(struct inode *i
 	if (!atomic_add_unless(&device_available, -1, 0))
 		return -EBUSY;
 
-	if ((filp->f_flags & O_ACCMODE) == O_RDWR)
+	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
+		atomic_inc(&device_available);
 		return -ENOSYS;
-
-	if(create_basic_memory_bitmaps())
+	}
+	if(create_basic_memory_bitmaps()) {
+		atomic_inc(&device_available);
 		return -ENOMEM;
-
+	}
 	nonseekable_open(inode, filp);
 	data = &snapshot_state;
 	filp->private_data = data;

[PATCH -mm 2/2] swsusp: Use GFP_KERNEL for creating basic data structures

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Make swsusp call create_basic_memory_bitmaps() before processes are frozen, so
that GFP_KERNEL allocations can be made in it.  Additionally, ensure that the
swsusp's userland interface won't be used while either pm_suspend_disk()
or software_resume() is being executed.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 kernel/power/disk.c     |   37 ++++++++++++++++++++++++++-----------
 kernel/power/power.h    |    3 +++
 kernel/power/snapshot.c |    8 ++++----
 kernel/power/user.c     |   10 +++++-----
 4 files changed, 38 insertions(+), 20 deletions(-)

Index: linux-2.6.21-rc4/kernel/power/disk.c
===================================================================
--- linux-2.6.21-rc4.orig/kernel/power/disk.c
+++ linux-2.6.21-rc4/kernel/power/disk.c
@@ -119,28 +119,33 @@ int pm_suspend_disk(void)
 {
 	int error;
 
+	/* The snapshot device should not be opened while we're running */
+	if (!atomic_add_unless(&snapshot_device_available, -1, 0))
+		return -EBUSY;
+
+	/* Allocate memory management structures */
+	error = create_basic_memory_bitmaps();
+	if (error)
+		goto Exit;
+
 	error = prepare_processes();
 	if (error)
-		return error;
+		goto Finish;
 
 	if (pm_disk_mode == PM_DISK_TESTPROC) {
 		printk("swsusp debug: Waiting for 5 seconds.\n");
 		mdelay(5000);
 		goto Thaw;
 	}
-	/* Allocate memory management structures */
-	error = create_basic_memory_bitmaps();
-	if (error)
-		goto Thaw;
 
 	/* Free memory before shutting down devices. */
 	error = swsusp_shrink_memory();
 	if (error)
-		goto Finish;
+		goto Thaw;
 
 	error = platform_prepare();
 	if (error)
-		goto Finish;
+		goto Thaw;
 
 	suspend_console();
 	error = device_suspend(PMSG_FREEZE);
@@ -175,7 +180,7 @@ int pm_suspend_disk(void)
 			power_down(pm_disk_mode);
 		else {
 			swsusp_free();
-			goto Finish;
+			goto Thaw;
 		}
 	} else {
 		pr_debug("PM: Image restored successfully.\n");
@@ -188,10 +193,12 @@ int pm_suspend_disk(void)
 	platform_finish();
 	device_resume();
 	resume_console();
- Finish:
-	free_basic_memory_bitmaps();
  Thaw:
 	unprepare_processes();
+ Finish:
+	free_basic_memory_bitmaps();
+ Exit:
+	atomic_inc(&snapshot_device_available);
 	return error;
 }
 
@@ -239,9 +246,15 @@ static int software_resume(void)
 	if (error)
 		goto Unlock;
 
+	/* The snapshot device should not be opened while we're running */
+	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
+		error = -EBUSY;
+		goto Unlock;
+	}
+
 	error = create_basic_memory_bitmaps();
 	if (error)
-		goto Unlock;
+		goto Finish;
 
 	pr_debug("PM: Preparing processes for restore.\n");
 	error = prepare_processes();
@@ -287,6 +300,8 @@ static int software_resume(void)
 	unprepare_processes();
  Done:
 	free_basic_memory_bitmaps();
+ Finish:
+	atomic_inc(&snapshot_device_available);
 	/* For success case, the suspend path will release the lock */
  Unlock:
 	mutex_unlock(&pm_mutex);
Index: linux-2.6.21-rc4/kernel/power/power.h
===================================================================
--- linux-2.6.21-rc4.orig/kernel/power/power.h
+++ linux-2.6.21-rc4/kernel/power/power.h
@@ -141,6 +141,9 @@ struct resume_swap_area {
 #define PMOPS_ENTER	2
 #define PMOPS_FINISH	3
 
+/* If unset, the snapshot device cannot be open. */
+extern atomic_t snapshot_device_available;
+
 /**
  *	The bitmap is used for tracing allocated swap pages
  *
Index: linux-2.6.21-rc4/kernel/power/snapshot.c
===================================================================
--- linux-2.6.21-rc4.orig/kernel/power/snapshot.c
+++ linux-2.6.21-rc4/kernel/power/snapshot.c
@@ -733,19 +733,19 @@ int create_basic_memory_bitmaps(void)
 
 	BUG_ON(forbidden_pages_map || free_pages_map);
 
-	bm1 = kzalloc(sizeof(struct memory_bitmap), GFP_ATOMIC);
+	bm1 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
 	if (!bm1)
 		return -ENOMEM;
 
-	error = memory_bm_create(bm1, GFP_ATOMIC | __GFP_COLD, PG_ANY);
+	error = memory_bm_create(bm1, GFP_KERNEL, PG_ANY);
 	if (error)
 		goto Free_first_object;
 
-	bm2 = kzalloc(sizeof(struct memory_bitmap), GFP_ATOMIC);
+	bm2 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
 	if (!bm2)
 		goto Free_first_bitmap;
 
-	error = memory_bm_create(bm2, GFP_ATOMIC | __GFP_COLD, PG_ANY);
+	error = memory_bm_create(bm2, GFP_KERNEL, PG_ANY);
 	if (error)
 		goto Free_second_object;
 
Index: linux-2.6.21-rc4/kernel/power/user.c
===================================================================
--- linux-2.6.21-rc4.orig/kernel/power/user.c
+++ linux-2.6.21-rc4/kernel/power/user.c
@@ -40,21 +40,21 @@ static struct snapshot_data {
 	char platform_suspend;
 } snapshot_state;
 
-static atomic_t device_available = ATOMIC_INIT(1);
+atomic_t snapshot_device_available = ATOMIC_INIT(1);
 
 static int snapshot_open(struct inode *inode, struct file *filp)
 {
 	struct snapshot_data *data;
 
-	if (!atomic_add_unless(&device_available, -1, 0))
+	if (!atomic_add_unless(&snapshot_device_available, -1, 0))
 		return -EBUSY;
 
 	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
-		atomic_inc(&device_available);
+		atomic_inc(&snapshot_device_available);
 		return -ENOSYS;
 	}
 	if(create_basic_memory_bitmaps()) {
-		atomic_inc(&device_available);
+		atomic_inc(&snapshot_device_available);
 		return -ENOMEM;
 	}
 	nonseekable_open(inode, filp);
@@ -92,7 +92,7 @@ static int snapshot_release(struct inode
 		enable_nonboot_cpus();
 		mutex_unlock(&pm_mutex);
 	}
-	atomic_inc(&device_available);
+	atomic_inc(&snapshot_device_available);
 	return 0;
 }
 

Re: [PATCH -mm 1/2] swsusp: Fix error paths in snapshot_open

[Pavel Machek]

Hi!

> We forget to increase device_available if there's an error in snapshot_open(),
> so the snapshot device cannot be open at all after snapshot_open() has returned
> an error.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

ACK.

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