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Revision 84811412464d66fcf73661a279aa1d7985166495 authored by Prashant Malani on 20 November 2019, 19:40:21 UTC, committed by David S. Miller on 20 November 2019, 20:48:13 UTC 
r8152: Re-order napi_disable in rtl8152_close
 
Both rtl_work_func_t() and rtl8152_close() call napi_disable().
Since the two calls aren't protected by a lock, if the close
function starts executing before the work function, we can get into a
situation where the napi_disable() function is called twice in
succession (first by rtl8152_close(), then by set_carrier()).

In such a situation, the second call would loop indefinitely, since
rtl8152_close() doesn't call napi_enable() to clear the NAPI_STATE_SCHED
bit.

The rtl8152_close() function in turn issues a
cancel_delayed_work_sync(), and so it would wait indefinitely for the
rtl_work_func_t() to complete. Since rtl8152_close() is called by a
process holding rtnl_lock() which is requested by other processes, this
eventually leads to a system deadlock and crash.

Re-order the napi_disable() call to occur after the work function
disabling and urb cancellation calls are issued.

Change-Id: I6ef0b703fc214998a037a68f722f784e1d07815e
Reported-by: http://crbug.com/1017928
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent b172845
Raw File
buffer_head_io.h 
/* SPDX-License-Identifier: GPL-2.0-or-later */
/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * ocfs2_buffer_head.h
 *
 * Buffer cache handling functions defined
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 */

#ifndef OCFS2_BUFFER_HEAD_IO_H
#define OCFS2_BUFFER_HEAD_IO_H

#include <linux/buffer_head.h>

int ocfs2_write_block(struct ocfs2_super          *osb,
		      struct buffer_head  *bh,
		      struct ocfs2_caching_info   *ci);
int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
			   unsigned int nr, struct buffer_head *bhs[]);

/*
 * If not NULL, validate() will be called on a buffer that is freshly
 * read from disk.  It will not be called if the buffer was in cache.
 * Note that if validate() is being used for this buffer, it needs to
 * be set even for a READAHEAD call, as it marks the buffer for later
 * validation.
 */
int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
		      struct buffer_head *bhs[], int flags,
		      int (*validate)(struct super_block *sb,
				      struct buffer_head *bh));

int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
				struct buffer_head *bh);

#define OCFS2_BH_IGNORE_CACHE      1
#define OCFS2_BH_READAHEAD         8

static inline int ocfs2_read_block(struct ocfs2_caching_info *ci, u64 off,
				   struct buffer_head **bh,
				   int (*validate)(struct super_block *sb,
						   struct buffer_head *bh))
{
	int status = 0;

	if (bh == NULL) {
		printk("ocfs2: bh == NULL\n");
		status = -EINVAL;
		goto bail;
	}

	status = ocfs2_read_blocks(ci, off, 1, bh, 0, validate);

bail:
	return status;
}

#endif /* OCFS2_BUFFER_HEAD_IO_H */
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