linux-kernel - Re: userspace firmware load fails with current linux-next

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Message-ID: <20131023124333.356d0e15@ipc1.ka-ro>
Date:	Wed, 23 Oct 2013 12:43:33 +0200
From:	Lothar Waßmann <LW@...O-electronics.de>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	tj@...nel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, tom.leiming@...il.com,
	gregkh@...uxfoundation.org
Subject: Re: userspace firmware load fails with current linux-next

Hi,

Ming Lei wrote:
> On Wed, 23 Oct 2013 11:06:18 +0200
> Lothar Waßmann <LW@...O-electronics.de> wrote:
> 
[...]
> > Or is it an unintended side effect of some recent change?
> 
> Maybe yes, could you test below patch?
> 
> Tejun, looks we need to keep special attention on zero size of bin file
> as before, could you comment at the patch?
> 
> --
> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> index 5d818df..366ae8d 100644
> --- a/fs/sysfs/file.c
> +++ b/fs/sysfs/file.c
> @@ -277,7 +277,7 @@ static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
>  	ssize_t len = min_t(size_t, count, PAGE_SIZE);
>  	char *buf;
>  
> -	if (sysfs_is_bin(of->sd)) {
> +	if (sysfs_is_bin(of->sd) && size) {
>  		loff_t size = file_inode(file)->i_size;
>  
>  		if (size <= *ppos)
> 
> 
> 
The patch as is produces a build error, because 'size' is only defined
after the 'if' statement.

The modified patch below works for me.

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 5d818df..709d6f5 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -277,7 +277,7 @@ static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
 	ssize_t len = min_t(size_t, count, PAGE_SIZE);
 	char *buf;
 
-	if (sysfs_is_bin(of->sd)) {
+	if (sysfs_is_bin(of->sd) && file_inode(file)->i_size) {
 		loff_t size = file_inode(file)->i_size;
 
 		if (size <= *ppos)



Lothar Waßmann
-- 
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