From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>
Subject: Re: [RFC cr-pipe-v13][PATCH 2/3] Checkpoint open pipes
Date: Fri, 06 Feb 2009 18:20:27 +0100
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To: Dave Hansen <dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Nathan Lynch <ntl-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org>
List-Id: containers.vger.kernel.org

Dave Hansen wrote:
> On Thu, 2009-02-05 at 20:26 -0600, Nathan Lynch wrote:
>> On Thu, 05 Feb 2009 10:45:55 +0100
>> Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org> wrote:
>>>> +/* cr_write_pipebuf - dump contents of a pipe/fifo (assume i_mutex taken) */
>>>> +static int cr_write_pipebuf(struct cr_ctx *ctx, struct pipe_inode_info *pipe)
>>>> +{
>>>> +	struct cr_hdr h;
>>>> +	void *kbuf, *addr;
>>>> +	int i, ret = 0;
>>>> +
>>>> +	kbuf = (void *) __get_free_page(GFP_KERNEL);
>>> this can sleep and inode->i_mutex is locked.
>> Generally, it is okay to perform operations that may sleep while
>> holding a mutex (not so with spinlocks, though).  Unless the page
>> allocator could try to acquire the same inode->i_mutex, this code
>> should be fine, no?
> 
> Sleeping inside mutexes is OK.  In general, they're drop-in compatible
> with semaphore behavior.

what about the vfs_write() ? 

C.