mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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7d47618a2a
Move the sysfs_create_group to iwl_ucode_callback after we
have safely got the firmware.
The motivation to do this comes from a warning from lockdep which detected
that we request priv->mutex while holding s_active during a sysfs request
(show_statistics in the example copy pasted). The reverse order exists upon
request_firmware: request_firmware which is a sysfs operation
that requires s_active is run under priv->mutex.
This ensures that we don't get sysfs request before we finish to request
the firmware, avoiding this deadlock.
=======================================================
[ INFO: possible circular locking dependency detected ]
-------------------------------------------------------
cat/2595 is trying to acquire lock:
(&priv->mutex){+.+.+.}, at: [<facfa598>] show_statistics+0x48/0x100 [iwlagn]
but task is already holding lock:
(s_active){++++.+}, at: [<c0580ebd>] sysfs_get_active_two+0x1d/0x50
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (s_active){++++.+}:
[<c0489b74>] __lock_acquire+0xc44/0x1230
[<c048a1ed>] lock_acquire+0x8d/0x110
[<c0581499>] sysfs_addrm_finish+0xe9/0x180
[<c057f64a>] sysfs_hash_and_remove+0x4a/0x80
[<c05829d4>] sysfs_remove_group+0x44/0xd0
[<c0714b75>] dpm_sysfs_remove+0x15/0x20
[<c070dac8>] device_del+0x38/0x170
[<c070dc1e>] device_unregister+0x1e/0x60
[<c071838d>] _request_firmware+0x29d/0x550
[<c07186c7>] request_firmware+0x17/0x20
[<fad01bf1>] iwl_mac_start+0xb1/0x1230 [iwlagn]
[<fa46ba06>] ieee80211_open+0x436/0x6f0 [mac80211]
[<c0808cd2>] dev_open+0x92/0xf0
[<c0808b2b>] dev_change_flags+0x7b/0x190
[<c08148e8>] do_setlink+0x178/0x3b0
[<c0815169>] rtnl_setlink+0xf9/0x130
[<c081453b>] rtnetlink_rcv_msg+0x1bb/0x1f0
[<c0827ce6>] netlink_rcv_skb+0x86/0xa0
[<c081436c>] rtnetlink_rcv+0x1c/0x30
[<c08279c3>] netlink_unicast+0x263/0x290
[<c0828768>] netlink_sendmsg+0x1c8/0x2a0
[<c07f85fd>] sock_sendmsg+0xcd/0x100
[<c07f964d>] sys_sendmsg+0x15d/0x290
[<c07f9e6b>] sys_socketcall+0xeb/0x2a0
[<c040ad9f>] sysenter_do_call+0x12/0x38
-> #0 (&priv->mutex){+.+.+.}:
[<c0489f84>] __lock_acquire+0x1054/0x1230
[<c048a1ed>] lock_acquire+0x8d/0x110
[<c08bb358>] __mutex_lock_common+0x58/0x470
[<c08bb84a>] mutex_lock_nested+0x3a/0x50
[<facfa598>] show_statistics+0x48/0x100 [iwlagn]
[<c070d219>] dev_attr_show+0x29/0x50
[<c057fecd>] sysfs_read_file+0xdd/0x190
[<c052880f>] vfs_read+0x9f/0x190
[<c0528d22>] sys_read+0x42/0x70
[<c040ad9f>] sysenter_do_call+0x12/0x38
other info that might help us debug this:
3 locks held by cat/2595:
#0: (&buffer->mutex){+.+.+.}, at: [<c057fe25>] sysfs_read_file+0x35/0x190
#1: (s_active){++++.+}, at: [<c0580ecd>] sysfs_get_active_two+0x2d/0x50
#2: (s_active){++++.+}, at: [<c0580ebd>] sysfs_get_active_two+0x1d/0x50
stack backtrace:
Pid: 2595, comm: cat Not tainted 2.6.33-tp-rc4 #2
Call Trace:
[<c08b99ab>] ? printk+0x1d/0x22
[<c0487752>] print_circular_bug+0xc2/0xd0
[<c0489f84>] __lock_acquire+0x1054/0x1230
[<c0478d81>] ? sched_clock_cpu+0x121/0x180
[<c048a1ed>] lock_acquire+0x8d/0x110
[<facfa598>] ? show_statistics+0x48/0x100 [iwlagn]
[<c08bb358>] __mutex_lock_common+0x58/0x470
[<facfa598>] ? show_statistics+0x48/0x100 [iwlagn]
[<c08bb84a>] mutex_lock_nested+0x3a/0x50
[<facfa598>] ? show_statistics+0x48/0x100 [iwlagn]
[<facfa598>] show_statistics+0x48/0x100 [iwlagn]
[<c0580cf9>] ? sysfs_get_active+0x69/0xb0
[<facfa550>] ? show_statistics+0x0/0x100 [iwlagn]
[<c070d219>] dev_attr_show+0x29/0x50
[<c057fecd>] sysfs_read_file+0xdd/0x190
[<c05ff314>] ? security_file_permission+0x14/0x20
[<c0528242>] ? rw_verify_area+0x62/0xd0
[<c052880f>] vfs_read+0x9f/0x190
[<c047745b>] ? up_read+0x1b/0x30
[<c057fdf0>] ? sysfs_read_file+0x0/0x190
[<c04af3b4>] ? audit_syscall_entry+0x1f4/0x220
[<c0528d22>] sys_read+0x42/0x70
[<c040ad9f>] sysenter_do_call+0x12/0x38
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
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|---|---|---|
| .. | ||
| accessibility | ||
| acpi | ||
| amba | ||
| ata | ||
| atm | ||
| auxdisplay | ||
| base | ||
| block | ||
| bluetooth | ||
| cdrom | ||
| char | ||
| clocksource | ||
| connector | ||
| cpufreq | ||
| cpuidle | ||
| crypto | ||
| dca | ||
| dio | ||
| dma | ||
| edac | ||
| eisa | ||
| firewire | ||
| firmware | ||
| gpio | ||
| gpu | ||
| hid | ||
| hwmon | ||
| i2c | ||
| ide | ||
| idle | ||
| ieee1394 | ||
| ieee802154 | ||
| infiniband | ||
| input | ||
| isdn | ||
| leds | ||
| lguest | ||
| macintosh | ||
| mca | ||
| md | ||
| media | ||
| memstick | ||
| message | ||
| mfd | ||
| misc | ||
| mmc | ||
| mtd | ||
| net | ||
| nubus | ||
| of | ||
| oprofile | ||
| parisc | ||
| parport | ||
| pci | ||
| pcmcia | ||
| platform | ||
| pnp | ||
| power | ||
| pps | ||
| ps3 | ||
| rapidio | ||
| regulator | ||
| rtc | ||
| s390 | ||
| sbus | ||
| scsi | ||
| serial | ||
| sfi | ||
| sh | ||
| sn | ||
| spi | ||
| ssb | ||
| staging | ||
| tc | ||
| telephony | ||
| thermal | ||
| uio | ||
| usb | ||
| uwb | ||
| vhost | ||
| video | ||
| virtio | ||
| vlynq | ||
| w1 | ||
| watchdog | ||
| xen | ||
| zorro | ||
| Kconfig | ||
| Makefile | ||