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Revision c331eb04b995ad276a7ece4608326f1db4e137d8 authored by NeilBrown on 31 May 2006, 04:27:13 UTC, committed by Linus Torvalds on 31 May 2006, 23:27:11 UTC 
[PATCH] md: Fix badness in sysfs_notify caused by md_new_event
 
From: NeilBrown <neilb@suse.de>

If an error is reported by a drive in a RAID array (which is done via
bi_end_io - in interrupt context), we call md_error and md_new_event which
calls sysfs_notify.  However sysfs_notify grabs a mutex and so cannot be
called in interrupt context.

This patch just creates a variant of md_new_event which avoids the sysfs
call, and uses that.  A better fix for later is to arrange for the event to
be called from user-context.

Note: avoiding the sysfs call isn't a problem as an error will not, by
itself, modify the sync_action attribute.  (We do still need to
wake_up(&md_event_waiters) as an error by itself will modify /proc/mdstat).

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent a835fa7
Raw File
msgutil.c 
/*
 * linux/ipc/util.c
 * Copyright (C) 1999, 2004 Manfred Spraul
 *
 * This file is released under GNU General Public Licence version 2 or
 * (at your option) any later version.
 *
 * See the file COPYING for more details.
 */

#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/ipc.h>
#include <asm/uaccess.h>

#include "util.h"

struct msg_msgseg {
	struct msg_msgseg* next;
	/* the next part of the message follows immediately */
};

#define DATALEN_MSG	(PAGE_SIZE-sizeof(struct msg_msg))
#define DATALEN_SEG	(PAGE_SIZE-sizeof(struct msg_msgseg))

struct msg_msg *load_msg(const void __user *src, int len)
{
	struct msg_msg *msg;
	struct msg_msgseg **pseg;
	int err;
	int alen;

	alen = len;
	if (alen > DATALEN_MSG)
		alen = DATALEN_MSG;

	msg = (struct msg_msg *)kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
	if (msg == NULL)
		return ERR_PTR(-ENOMEM);

	msg->next = NULL;
	msg->security = NULL;

	if (copy_from_user(msg + 1, src, alen)) {
		err = -EFAULT;
		goto out_err;
	}

	len -= alen;
	src = ((char __user *)src) + alen;
	pseg = &msg->next;
	while (len > 0) {
		struct msg_msgseg *seg;
		alen = len;
		if (alen > DATALEN_SEG)
			alen = DATALEN_SEG;
		seg = (struct msg_msgseg *)kmalloc(sizeof(*seg) + alen,
						 GFP_KERNEL);
		if (seg == NULL) {
			err = -ENOMEM;
			goto out_err;
		}
		*pseg = seg;
		seg->next = NULL;
		if (copy_from_user(seg + 1, src, alen)) {
			err = -EFAULT;
			goto out_err;
		}
		pseg = &seg->next;
		len -= alen;
		src = ((char __user *)src) + alen;
	}

	err = security_msg_msg_alloc(msg);
	if (err)
		goto out_err;

	return msg;

out_err:
	free_msg(msg);
	return ERR_PTR(err);
}

int store_msg(void __user *dest, struct msg_msg *msg, int len)
{
	int alen;
	struct msg_msgseg *seg;

	alen = len;
	if (alen > DATALEN_MSG)
		alen = DATALEN_MSG;
	if (copy_to_user(dest, msg + 1, alen))
		return -1;

	len -= alen;
	dest = ((char __user *)dest) + alen;
	seg = msg->next;
	while (len > 0) {
		alen = len;
		if (alen > DATALEN_SEG)
			alen = DATALEN_SEG;
		if (copy_to_user(dest, seg + 1, alen))
			return -1;
		len -= alen;
		dest = ((char __user *)dest) + alen;
		seg = seg->next;
	}
	return 0;
}

void free_msg(struct msg_msg *msg)
{
	struct msg_msgseg *seg;

	security_msg_msg_free(msg);

	seg = msg->next;
	kfree(msg);
	while (seg != NULL) {
		struct msg_msgseg *tmp = seg->next;
		kfree(seg);
		seg = tmp;
	}
}
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