Re: + zram-rework-reset-and-destroy-path-fix.patch added to -mm tree

Re: + zram-rework-reset-and-destroy-path-fix.patch added to -mm tree

[Sergey Senozhatsky]

On (02/03/15 15:11), akpm@linux-foundation.org wrote:
> tweak comment
> 

Thank you, sir.

Andrew, can you please squash the following patch?

---

>From 22f0be96df55513a3d764ea880d5b3e99669f8f7 Mon Sep 17 00:00:00 2001
From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Date: Wed, 4 Feb 2015 09:59:06 +0900
Subject: [PATCH] zram: set default dev_id value to zero in zram_init()

Set dev_id to zero and fix zram_devices allocation error handling
path, can pass uninit dev_id to destroy_devices().

cosmetic:
change destroy_devices() message from pr_debug() to pr_info(), as
proposed by Minchan Kim.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 79c5da9..0bb4fa0 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1138,12 +1138,12 @@ static void destroy_devices(unsigned int nr)
 
 	kfree(zram_devices);
 	unregister_blkdev(zram_major, "zram");
-	pr_debug("Destroyed %u device(s)\n", nr);
+	pr_info("Destroyed %u device(s)\n", nr);
 }
 
 static int __init zram_init(void)
 {
-	int ret, dev_id;
+	int ret = -ENOMEM, dev_id = 0;
 
 	if (num_devices > max_num_devices) {
 		pr_warn("Invalid value for num_devices: %u\n",
@@ -1159,10 +1159,8 @@ static int __init zram_init(void)
 
 	/* Allocate the device array and initialize each one */
 	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
-	if (!zram_devices) {
-		ret = -ENOMEM;
+	if (!zram_devices)
 		goto out_error;
-	}
 
 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
 		ret = create_device(&zram_devices[dev_id], dev_id);
-- 
2.3.0.rc2

Re: + zram-rework-reset-and-destroy-path-fix.patch added to -mm tree

[Andrew Morton]

On Wed, 4 Feb 2015 10:07:20 +0900 Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> wrote:

> Set dev_id to zero and fix zram_devices allocation error handling
> path, can pass uninit dev_id to destroy_devices().
> 
> cosmetic:
> change destroy_devices() message from pr_debug() to pr_info(), as
> proposed by Minchan Kim.
> 

Seems unnecessarily complicated.  What about

--- a/drivers/block/zram/zram_drv.c~zram-rework-reset-and-destroy-path-fix-2-fix
+++ a/drivers/block/zram/zram_drv.c
@@ -1141,7 +1141,8 @@ static void destroy_devices(unsigned int
 
 static int __init zram_init(void)
 {
-	int ret = -ENOMEM, dev_id = 0;
+	int ret;
+	int dev_id;
 
 	if (num_devices > max_num_devices) {
 		pr_warn("Invalid value for num_devices: %u\n",
@@ -1157,20 +1158,23 @@ static int __init zram_init(void)
 
 	/* Allocate the device array and initialize each one */
 	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
-	if (!zram_devices)
-		goto out_error;
+	if (!zram_devices) {
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
 		ret = create_device(&zram_devices[dev_id], dev_id);
 		if (ret)
-			goto out_error;
+			goto out_devices;
 	}
 
 	pr_info("Created %u device(s)\n", num_devices);
 	return 0;
 
-out_error:
+out_devices:
 	destroy_devices(dev_id);
+out:
 	return ret;
 }

which yields

static int __init zram_init(void)
{
	int ret;
	int dev_id;

	if (num_devices > max_num_devices) {
		pr_warn("Invalid value for num_devices: %u\n",
				num_devices);
		return -EINVAL;
	}

	zram_major = register_blkdev(0, "zram");
	if (zram_major <= 0) {
		pr_warn("Unable to get major number\n");
		return -EBUSY;
	}

	/* Allocate the device array and initialize each one */
	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
	if (!zram_devices) {
		ret = -ENOMEM;
		goto out;
	}

	for (dev_id = 0; dev_id < num_devices; dev_id++) {
		ret = create_device(&zram_devices[dev_id], dev_id);
		if (ret)
			goto out_devices;
	}

	pr_info("Created %u device(s)\n", num_devices);
	return 0;

out_devices:
	destroy_devices(dev_id);
out:
	return ret;
}

 
_

Re: + zram-rework-reset-and-destroy-path-fix.patch added to -mm tree

[Sergey Senozhatsky]

Hello,
sorry for late response

On (02/04/15 14:29), Andrew Morton wrote:
> Seems unnecessarily complicated.  What about
> 
> --- a/drivers/block/zram/zram_drv.c~zram-rework-reset-and-destroy-path-fix-2-fix
> +++ a/drivers/block/zram/zram_drv.c
> @@ -1141,7 +1141,8 @@ static void destroy_devices(unsigned int
>  
>  static int __init zram_init(void)
>  {
> -	int ret = -ENOMEM, dev_id = 0;
> +	int ret;
> +	int dev_id;
>  
>  	if (num_devices > max_num_devices) {
>  		pr_warn("Invalid value for num_devices: %u\n",
> @@ -1157,20 +1158,23 @@ static int __init zram_init(void)
>  
>  	/* Allocate the device array and initialize each one */
>  	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
> -	if (!zram_devices)
> -		goto out_error;
> +	if (!zram_devices) {
> +		ret = -ENOMEM;

we need to rollback `zram_major = register_blkdev(0, "zram");'
which is done in destroy_devices().

	-ss

Re: + zram-rework-reset-and-destroy-path-fix.patch added to -mm tree

[Sergey Senozhatsky]

On (02/04/15 14:29), Andrew Morton wrote:
> which yields
> 

/* not sure if my previous email has been delived, seems there are some
connectivity problems on my side */


we need to unregister_blkdev(), 'out' label does not do it.

how about the following one (looks simple):

> static int __init zram_init(void)
> {
> 	int ret;
> 	int dev_id;
> 
> 	if (num_devices > max_num_devices) {
> 		pr_warn("Invalid value for num_devices: %u\n",
> 				num_devices);
> 		return -EINVAL;
> 	}
> 
> 	zram_major = register_blkdev(0, "zram");
> 	if (zram_major <= 0) {
> 		pr_warn("Unable to get major number\n");
> 		return -EBUSY;
> 	}
> 
> 	/* Allocate the device array and initialize each one */
> 	zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
> 	if (!zram_devices) {
-               ret = -ENOMEM;
-               goto out_error;
+               unregister_blkdev(zram_major, "zram");
+               return -ENOMEM;
> 	}
> 
> 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
> 		ret = create_device(&zram_devices[dev_id], dev_id);
> 		if (ret)
> 			goto out_devices;
> 	}
> 
> 	pr_info("Created %u device(s)\n", num_devices);
> 	return 0;
> 
> out_devices:
> 	destroy_devices(dev_id);
- out:
> 	return ret;
> }