[kernel/f16] Resolves: bz 771058

[Neil Horman]

commit 114a35487e42b55901c6ee295fd5efce1b98d586
Author: Neil Horman <nhorman at tuxdriver.com>
Date:   Wed Jan 4 16:05:07 2012 -0500

    Resolves: bz 771058

 kernel.spec                 |    9 ++++
 msi-irq-sysfs-warning.patch |   87 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+), 0 deletions(-)
---
diff --git a/kernel.spec b/kernel.spec
index 9444c21..6e191dd 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -869,6 +869,9 @@ Patch50104: mwifiex-avoid-double-list_del-in-command-cancel-path.patch
 
 Patch22000: route-cache-garbage-collector.patch
 
+#rhbz 771058
+Patch22100: msi-irq-sysfs-warning.patch
+
 %endif
 
 BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root
@@ -1601,6 +1604,9 @@ ApplyPatch Bluetooth-Add-support-for-BCM20702A0.patch
 #rhbz 771678
 ApplyPatch KVM-fix-device-assignment-permissions.patch
 
+#rhbz 771058
+ApplyPatch msi-irq-sysfs-warning.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2376,6 +2382,9 @@ fi
 # and build.
 
 %changelog
+* Wed Jan 04 2012 Neil Horman <nhorman at redhat.com>
+- Fix warning about msi sysfs refcount (bz 771058)
+
 * Wed Jan 04 2012 Dave Jones <davej at redhat.com>
 - Add Dell Studio 1557 to pci=nocrs blacklist. (rhbz 769657)
 
diff --git a/msi-irq-sysfs-warning.patch b/msi-irq-sysfs-warning.patch
new file mode 100644
index 0000000..dce440e
--- /dev/null
+++ b/msi-irq-sysfs-warning.patch
@@ -0,0 +1,87 @@
+commit 3ff0e97a1bc3059bfbcc1d864c5d4ff5f8d3c2b9
+Author: Neil Horman <nhorman at tuxdriver.com>
+Date:   Tue Jan 3 10:17:21 2012 -0500
+
+    msi: fix imbalanced refcount of msi irq sysfs objects
+    
+    This warning was recently reported to me:
+    
+    ------------[ cut here ]------------
+    WARNING: at lib/kobject.c:595 kobject_put+0x50/0x60()
+    Hardware name: VMware Virtual Platform
+    kobject: '(null)' (ffff880027b0df40): is not initialized, yet kobject_put() is
+    being called.
+    Modules linked in: vmxnet3(+) vmw_balloon i2c_piix4 i2c_core shpchp raid10
+    vmw_pvscsi
+    Pid: 630, comm: modprobe Tainted: G        W   3.1.6-1.fc16.x86_64 #1
+    Call Trace:
+     [<ffffffff8106b73f>] warn_slowpath_common+0x7f/0xc0
+     [<ffffffff8106b836>] warn_slowpath_fmt+0x46/0x50
+     [<ffffffff810da293>] ? free_desc+0x63/0x70
+     [<ffffffff812a9aa0>] kobject_put+0x50/0x60
+     [<ffffffff812e4c25>] free_msi_irqs+0xd5/0x120
+     [<ffffffff812e524c>] pci_enable_msi_block+0x24c/0x2c0
+     [<ffffffffa017c273>] vmxnet3_alloc_intr_resources+0x173/0x240 [vmxnet3]
+     [<ffffffffa0182e94>] vmxnet3_probe_device+0x615/0x834 [vmxnet3]
+     [<ffffffff812d141c>] local_pci_probe+0x5c/0xd0
+     [<ffffffff812d2cb9>] pci_device_probe+0x109/0x130
+     [<ffffffff8138ba2c>] driver_probe_device+0x9c/0x2b0
+     [<ffffffff8138bceb>] __driver_attach+0xab/0xb0
+     [<ffffffff8138bc40>] ? driver_probe_device+0x2b0/0x2b0
+     [<ffffffff8138bc40>] ? driver_probe_device+0x2b0/0x2b0
+     [<ffffffff8138a8ac>] bus_for_each_dev+0x5c/0x90
+     [<ffffffff8138b63e>] driver_attach+0x1e/0x20
+     [<ffffffff8138b240>] bus_add_driver+0x1b0/0x2a0
+     [<ffffffffa0188000>] ? 0xffffffffa0187fff
+     [<ffffffff8138c246>] driver_register+0x76/0x140
+     [<ffffffff815ca414>] ? printk+0x51/0x53
+     [<ffffffffa0188000>] ? 0xffffffffa0187fff
+     [<ffffffff812d2996>] __pci_register_driver+0x56/0xd0
+     [<ffffffffa018803a>] vmxnet3_init_module+0x3a/0x3c [vmxnet3]
+     [<ffffffff81002042>] do_one_initcall+0x42/0x180
+     [<ffffffff810aad71>] sys_init_module+0x91/0x200
+     [<ffffffff815dccc2>] system_call_fastpath+0x16/0x1b
+    ---[ end trace 44593438a59a9558 ]---
+    Using INTx interrupt, #Rx queues: 1.
+    
+    It occurs when populate_msi_sysfs fails, which in turn causes free_msi_irqs to
+    be called.  Because populate_msi_sysfs fails, we never registered any of the
+    msi irq sysfs objects, but free_msi_irqs still calls kobject_del and kobject_put
+    on each of them, which gets flagged in the above stack trace.
+    
+    The fix is pretty straightforward.  We can key of the parent pointer in the
+    kobject.  It is only set if the kobject_init_and_add succededs in
+    populate_msi_sysfs.  If anything fails there, each kobject has its parent reset
+    to NULL
+    
+    Signed-off-by: Neil Horman <nhorman at tuxdriver.com>
+    CC: Jesse Barnes <jbarnes at virtuousgeek.org>
+    CC: Bjorn Helgaas <bhelgaas at google.com>
+    CC: Greg Kroah-Hartman <gregkh at suse.de>
+    CC: linux-pci at vger.kernel.org
+
+diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
+index 337e16a..82de95e 100644
+--- a/drivers/pci/msi.c
++++ b/drivers/pci/msi.c
+@@ -323,8 +323,18 @@ static void free_msi_irqs(struct pci_dev *dev)
+ 			if (list_is_last(&entry->list, &dev->msi_list))
+ 				iounmap(entry->mask_base);
+ 		}
+-		kobject_del(&entry->kobj);
+-		kobject_put(&entry->kobj);
++
++		/*
++		 * Its possible that we get into this path
++		 * When populate_msi_sysfs fails, which means the entries
++		 * were not registered with sysfs.  In that case don't
++		 * unregister them.
++		 */
++		if (entry->kobj.parent) {
++			kobject_del(&entry->kobj);
++			kobject_put(&entry->kobj);
++		}
++
+ 		list_del(&entry->list);
+ 		kfree(entry);
+ 	}