[PATCH 3.14 16/83] [SCSI] virtio-scsi: Skip setting affinity on uninitialized vq

From: Greg Kroah-Hartman
Date: Sun May 11 2014 - 15:58:34 EST

3.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Fam Zheng <famz@xxxxxxxxxx>

commit 0c8482ac92db5ac15792caf23b7f7df9e4f48ae1 upstream.

virtscsi_init calls virtscsi_remove_vqs on err, even before initializing
the vqs. The latter calls virtscsi_set_affinity, so let's check the
pointer there before setting affinity on it.

This fixes a panic when setting device's num_queues=2 on RHEL 6.5:

qemu-system-x86_64 ... \
-device virtio-scsi-pci,id=scsi0,addr=0x13,...,num_queues=2 \
-drive file=/stor/vm/dummy.raw,id=drive-scsi-disk,... \
-device scsi-hd,drive=drive-scsi-disk,...

[ 0.354734] scsi0 : Virtio SCSI HBA
[ 0.379504] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
[ 0.380141] IP: [<ffffffff814741ef>] __virtscsi_set_affinity+0x4f/0x120
[ 0.380141] PGD 0
[ 0.380141] Oops: 0000 [#1] SMP
[ 0.380141] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0+ #5
[ 0.380141] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007
[ 0.380141] task: ffff88003c9f0000 ti: ffff88003c9f8000 task.ti: ffff88003c9f8000
[ 0.380141] RIP: 0010:[<ffffffff814741ef>] [<ffffffff814741ef>] __virtscsi_set_affinity+0x4f/0x120
[ 0.380141] RSP: 0000:ffff88003c9f9c08 EFLAGS: 00010256
[ 0.380141] RAX: 0000000000000000 RBX: ffff88003c3a9d40 RCX: 0000000000001070
[ 0.380141] RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
[ 0.380141] RBP: ffff88003c9f9c28 R08: 00000000000136c0 R09: ffff88003c801c00
[ 0.380141] R10: ffffffff81475229 R11: 0000000000000008 R12: 0000000000000000
[ 0.380141] R13: ffffffff81cc7ca8 R14: ffff88003cac3d40 R15: ffff88003cac37a0
[ 0.380141] FS: 0000000000000000(0000) GS:ffff88003e400000(0000) knlGS:0000000000000000
[ 0.380141] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 0.380141] CR2: 0000000000000020 CR3: 0000000001c0e000 CR4: 00000000000006f0
[ 0.380141] Stack:
[ 0.380141] ffff88003c3a9d40 0000000000000000 ffff88003cac3d80 ffff88003cac3d40
[ 0.380141] ffff88003c9f9c48 ffffffff814742e8 ffff88003c26d000 ffff88003c26d000
[ 0.380141] ffff88003c9f9c68 ffffffff81474321 ffff88003c26d000 ffff88003c3a9d40
[ 0.380141] Call Trace:
[ 0.380141] [<ffffffff814742e8>] virtscsi_set_affinity+0x28/0x40
[ 0.380141] [<ffffffff81474321>] virtscsi_remove_vqs+0x21/0x50
[ 0.380141] [<ffffffff81475231>] virtscsi_init+0x91/0x240
[ 0.380141] [<ffffffff81365290>] ? vp_get+0x50/0x70
[ 0.380141] [<ffffffff81475544>] virtscsi_probe+0xf4/0x280
[ 0.380141] [<ffffffff81363ea5>] virtio_dev_probe+0xe5/0x140
[ 0.380141] [<ffffffff8144c669>] driver_probe_device+0x89/0x230
[ 0.380141] [<ffffffff8144c8ab>] __driver_attach+0x9b/0xa0
[ 0.380141] [<ffffffff8144c810>] ? driver_probe_device+0x230/0x230
[ 0.380141] [<ffffffff8144c810>] ? driver_probe_device+0x230/0x230
[ 0.380141] [<ffffffff8144ac1c>] bus_for_each_dev+0x8c/0xb0
[ 0.380141] [<ffffffff8144c499>] driver_attach+0x19/0x20
[ 0.380141] [<ffffffff8144bf28>] bus_add_driver+0x198/0x220
[ 0.380141] [<ffffffff8144ce9f>] driver_register+0x5f/0xf0
[ 0.380141] [<ffffffff81d27c91>] ? spi_transport_init+0x79/0x79
[ 0.380141] [<ffffffff8136403b>] register_virtio_driver+0x1b/0x30
[ 0.380141] [<ffffffff81d27d19>] init+0x88/0xd6
[ 0.380141] [<ffffffff81d27c18>] ? scsi_init_procfs+0x5b/0x5b
[ 0.380141] [<ffffffff81ce88a7>] do_one_initcall+0x7f/0x10a
[ 0.380141] [<ffffffff81ce8aa7>] kernel_init_freeable+0x14a/0x1de
[ 0.380141] [<ffffffff81ce8b3b>] ? kernel_init_freeable+0x1de/0x1de
[ 0.380141] [<ffffffff817dec20>] ? rest_init+0x80/0x80
[ 0.380141] [<ffffffff817dec29>] kernel_init+0x9/0xf0
[ 0.380141] [<ffffffff817e68fc>] ret_from_fork+0x7c/0xb0
[ 0.380141] [<ffffffff817dec20>] ? rest_init+0x80/0x80
[ 0.380141] RIP [<ffffffff814741ef>] __virtscsi_set_affinity+0x4f/0x120
[ 0.380141] RSP <ffff88003c9f9c08>
[ 0.380141] CR2: 0000000000000020
[ 0.380141] ---[ end trace 8074b70c3d5e1d73 ]---
[ 0.475018] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009
[ 0.475018]
[ 0.475068] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffff9fffffff)
[ 0.475068] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009

[jejb: checkpatch fixes]
Signed-off-by: Fam Zheng <famz@xxxxxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/scsi/virtio_scsi.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -750,8 +750,12 @@ static void __virtscsi_set_affinity(stru

vscsi->affinity_hint_set = true;
} else {
- for (i = 0; i < vscsi->num_queues; i++)
+ for (i = 0; i < vscsi->num_queues; i++) {
+ if (!vscsi->req_vqs[i].vq)
+ continue;
+
virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1);
+ }

vscsi->affinity_hint_set = false;
}


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