Files
linux_media/net/hsr/hsr_debugfs.c
Taehee Yoo 84bb59d773 hsr: avoid debugfs warning message when module is remove
When hsr module is being removed, debugfs_remove() is called to remove
both debugfs directory and file.

When module is being removed, module state is changed to
MODULE_STATE_GOING then exit() is called.
At this moment, module couldn't be held so try_module_get()
will be failed.

debugfs's open() callback tries to hold the module if .owner is existing.
If it fails, warning message is printed.

CPU0				CPU1
delete_module()
    try_stop_module()
    hsr_exit()			open() <-- WARNING
        debugfs_remove()

In order to avoid the warning message, this patch makes hsr module does
not set .owner. Unsetting .owner is safe because these are protected by
inode_lock().

Test commands:
    #SHELL1
    ip link add dummy0 type dummy
    ip link add dummy1 type dummy
    while :
    do
        ip link add hsr0 type hsr slave1 dummy0 slave2 dummy1
	modprobe -rv hsr
    done

    #SHELL2
    while :
    do
        cat /sys/kernel/debug/hsr0/node_table
    done

Splat looks like:
[  101.223783][ T1271] ------------[ cut here ]------------
[  101.230309][ T1271] debugfs file owner did not clean up at exit: node_table
[  101.230380][ T1271] WARNING: CPU: 3 PID: 1271 at fs/debugfs/file.c:309 full_proxy_open+0x10f/0x650
[  101.233153][ T1271] Modules linked in: hsr(-) dummy veth openvswitch nsh nf_conncount nf_nat nf_conntrack nf_d]
[  101.237112][ T1271] CPU: 3 PID: 1271 Comm: cat Tainted: G        W         5.5.0-rc1+ #204
[  101.238270][ T1271] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  101.240379][ T1271] RIP: 0010:full_proxy_open+0x10f/0x650
[  101.241166][ T1271] Code: 48 c1 ea 03 80 3c 02 00 0f 85 c1 04 00 00 49 8b 3c 24 e8 04 86 7e ff 84 c0 75 2d 4c 8
[  101.251985][ T1271] RSP: 0018:ffff8880ca22fa38 EFLAGS: 00010286
[  101.273355][ T1271] RAX: dffffc0000000008 RBX: ffff8880cc6e6200 RCX: 0000000000000000
[  101.274466][ T1271] RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff8880c4dd5c14
[  101.275581][ T1271] RBP: 0000000000000000 R08: fffffbfff2922f5d R09: 0000000000000000
[  101.276733][ T1271] R10: 0000000000000001 R11: 0000000000000000 R12: ffffffffc0551bc0
[  101.277853][ T1271] R13: ffff8880c4059a48 R14: ffff8880be50a5e0 R15: ffffffff941adaa0
[  101.278956][ T1271] FS:  00007f8871cda540(0000) GS:ffff8880da800000(0000) knlGS:0000000000000000
[  101.280216][ T1271] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  101.282832][ T1271] CR2: 00007f88717cfd10 CR3: 00000000b9440005 CR4: 00000000000606e0
[  101.283974][ T1271] Call Trace:
[  101.285328][ T1271]  do_dentry_open+0x63c/0xf50
[  101.286077][ T1271]  ? open_proxy_open+0x270/0x270
[  101.288271][ T1271]  ? __x64_sys_fchdir+0x180/0x180
[  101.288987][ T1271]  ? inode_permission+0x65/0x390
[  101.289682][ T1271]  path_openat+0x701/0x2810
[  101.290294][ T1271]  ? path_lookupat+0x880/0x880
[  101.290957][ T1271]  ? check_chain_key+0x236/0x5d0
[  101.291676][ T1271]  ? __lock_acquire+0xdfe/0x3de0
[  101.292358][ T1271]  ? sched_clock+0x5/0x10
[  101.292962][ T1271]  ? sched_clock_cpu+0x18/0x170
[  101.293644][ T1271]  ? find_held_lock+0x39/0x1d0
[  101.305616][ T1271]  do_filp_open+0x17a/0x270
[  101.306061][ T1271]  ? may_open_dev+0xc0/0xc0
[ ... ]

Fixes: fc4ecaeebd ("net: hsr: add debugfs support for display node list")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-25 16:35:35 -08:00

119 lines
3.2 KiB
C

/*
* hsr_debugfs code
* Copyright (C) 2019 Texas Instruments Incorporated
*
* Author(s):
* Murali Karicheri <m-karicheri2@ti.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation version 2.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/debugfs.h>
#include "hsr_main.h"
#include "hsr_framereg.h"
static void print_mac_address(struct seq_file *sfp, unsigned char *mac)
{
seq_printf(sfp, "%02x:%02x:%02x:%02x:%02x:%02x:",
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
}
/* hsr_node_table_show - Formats and prints node_table entries */
static int
hsr_node_table_show(struct seq_file *sfp, void *data)
{
struct hsr_priv *priv = (struct hsr_priv *)sfp->private;
struct hsr_node *node;
seq_puts(sfp, "Node Table entries\n");
seq_puts(sfp, "MAC-Address-A, MAC-Address-B, time_in[A], ");
seq_puts(sfp, "time_in[B], Address-B port\n");
rcu_read_lock();
list_for_each_entry_rcu(node, &priv->node_db, mac_list) {
/* skip self node */
if (hsr_addr_is_self(priv, node->macaddress_A))
continue;
print_mac_address(sfp, &node->macaddress_A[0]);
seq_puts(sfp, " ");
print_mac_address(sfp, &node->macaddress_B[0]);
seq_printf(sfp, "0x%lx, ", node->time_in[HSR_PT_SLAVE_A]);
seq_printf(sfp, "0x%lx ", node->time_in[HSR_PT_SLAVE_B]);
seq_printf(sfp, "0x%x\n", node->addr_B_port);
}
rcu_read_unlock();
return 0;
}
/* hsr_node_table_open - Open the node_table file
*
* Description:
* This routine opens a debugfs file node_table of specific hsr device
*/
static int
hsr_node_table_open(struct inode *inode, struct file *filp)
{
return single_open(filp, hsr_node_table_show, inode->i_private);
}
static const struct file_operations hsr_fops = {
.open = hsr_node_table_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
/* hsr_debugfs_init - create hsr node_table file for dumping
* the node table
*
* Description:
* When debugfs is configured this routine sets up the node_table file per
* hsr device for dumping the node_table entries
*/
int hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev)
{
int rc = -1;
struct dentry *de = NULL;
de = debugfs_create_dir(hsr_dev->name, NULL);
if (!de) {
pr_err("Cannot create hsr debugfs root\n");
return rc;
}
priv->node_tbl_root = de;
de = debugfs_create_file("node_table", S_IFREG | 0444,
priv->node_tbl_root, priv,
&hsr_fops);
if (!de) {
pr_err("Cannot create hsr node_table directory\n");
return rc;
}
priv->node_tbl_file = de;
return 0;
}
/* hsr_debugfs_term - Tear down debugfs intrastructure
*
* Description:
* When Debufs is configured this routine removes debugfs file system
* elements that are specific to hsr
*/
void
hsr_debugfs_term(struct hsr_priv *priv)
{
debugfs_remove(priv->node_tbl_file);
priv->node_tbl_file = NULL;
debugfs_remove(priv->node_tbl_root);
priv->node_tbl_root = NULL;
}