-----Original Message-----
From: Greg KH [mailto:greg@kroah.com]
Sent: Tuesday, July 05, 2011 12:10 PM
To: Haiyang Zhang
Cc: Hank Janssen; KY Srinivasan; Abhishek Kane (Mindtree Consulting PVT
LTD); gregkh@suse.de; linux-kernel@vger.kernel.org;
devel@linuxdriverproject.org; virtualization@lists.osdl.org; stable
Subject: Re: [PATCH 5/5] staging: hv: fix a kernel warning in
netvsc_linkstatus_callback()

On Fri, Jun 17, 2011 at 07:58:08AM -0700, Haiyang Zhang wrote:

quoted

netif_notify_peers() is not allowed in netvsc_linkstatus_callback() on

some

quoted

distros,

"distros"?  Huh?  You mean kernel versions right?

And this doesn't matter for the current kernel, right?  If not, then it
doesn't need to be applied.  If so, then it should.  Which is it?

It should be applied to both current kernel and stable kernels 2.6.32 and later.

quoted

because netvsc_linkstatus_callback() is within IRQ context. So we
move the first call to netif_notify_peers() into queued work as well,

but with

quoted

zero delay.

What happens if you don't have this patch applied?  What breaks?  Is it
just a warning?  Something else?

Without the patch, it will have this warning:

[  232.102605] WARNING: at kernel/mutex.c:198 __mutex_lock_slowpath+0x28d/0x2c0(
)
[  232.102605] Hardware name: Virtual Machine
[  232.272436] Modules linked in: hv_netvsc(C) hv_vmbus(C) lockd sunrpc nf_connt
rack_netbios_ns nf_conntrack_broadcast ipt_REJECT nf_conntrack_ipv4 nf_defrag_ip
v4 xt_state nf_conntrack iptable_filter ip_tables ip6t_REJECT xt_tcpudp ip6table
_filter ip6_tables x_tables ipv6 loop dm_mirror dm_multipath scsi_dh video therm
al sbs sbshc pci_slot hed fan container battery acpi_memhotplug ac power_supply
parport nvram sg sr_mod cdrom evdev processor button serio_raw floppy tpm_tis tp
m tpm_bios tulip i2c_piix4 i2c_core dm_region_hash dm_log dm_mod ide_gd_mod piix
 pata_acpi ide_pci_generic ide_core ata_piix ata_generic libata sd_mod scsi_mod
ext3 jbd mbcache [last unloaded: microcode]
[  232.935109] Pid: 0, comm: swapper Tainted: G         C  3.0.0-rc2-stable-0019
6-g06e8684 #4
[  232.939905] Call Trace:
[  232.942238]  [<c13008fd>] ? __mutex_lock_slowpath+0x28d/0x2c0
[  232.974990]  [<c1041a9c>] warn_slowpath_common+0x7c/0xa0
[  232.977701]  [<c13008fd>] ? __mutex_lock_slowpath+0x28d/0x2c0
[  232.980431]  [<c1041add>] warn_slowpath_null+0x1d/0x20
[  232.983403]  [<c13008fd>] __mutex_lock_slowpath+0x28d/0x2c0
[  232.995597]  [<c130093b>] mutex_lock+0xb/0x20
[  233.020191]  [<c127347d>] rtnl_lock+0xd/0x10
[  233.023275]  [<c127cf7b>] netif_notify_peers+0xb/0x20
[  233.026424]  [<e0e581d2>] netvsc_linkstatus_callback+0x142/0x230 [hv_netvsc]
[  233.051372]  [<e0e5c0df>] rndis_filter_receive+0x83f/0x8e0 [hv_netvsc]
[  233.062010]  [<e0e3c82e>] ? hv_ringbuffer_read+0x15e/0x200 [hv_vmbus]
[  233.065632]  [<e0e5a936>] netvsc_channel_cb+0x8e6/0xb10 [hv_netvsc]
[  233.069444]  [<e0e38743>] vmbus_onchannel_event+0x33/0x80 [hv_vmbus]
[  233.092295]  [<e0e37bb8>] vmbus_on_event+0xf8/0x180 [hv_vmbus]
[  233.104314]  [<c104850f>] tasklet_action+0x4f/0x100
[  233.106669]  [<c1047876>] __do_softirq+0x86/0x1e0
[  233.109376]  [<c10477f0>] ? local_bh_enable_ip+0xa0/0xa0
[  233.112031]  <IRQ>  [<c1047b6c>] ? irq_exit+0x8c/0xa0
[  233.133300]  [<c10040a5>] ? do_IRQ+0x45/0xb0
[  233.136307]  [<c1047b4e>] ? irq_exit+0x6e/0xa0
[  233.138901]  [<c101d149>] ? smp_apic_timer_interrupt+0x59/0x90
[  233.142796]  [<c1302db0>] ? common_interrupt+0x30/0x38
[  233.146401]  [<c1024be5>] ? native_safe_halt+0x5/0x10
[  233.149765]  [<c1009b00>] ? default_idle+0x70/0x130
[  233.154054]  [<c1001dda>] ? cpu_idle+0x8a/0xd0
[  233.157170]  [<c12eb4dd>] ? rest_init+0x7d/0x80
[  233.168628]  [<c14239e5>] ? start_kernel+0x315/0x3d0
[  233.171518]  [<c1423270>] ? parse_early_options+0x30/0x30
[  233.180398]  [<c1423078>] ? i386_start_kernel+0x78/0xc0
[  233.183514] ---[ end trace 3a5b5bc7486ad570 ]---
 

Please resend this with more information.

Will do (after Ky's patch series are resubmitted and applied).

Thanks,

- Haiyang