linux.git/drivers/char/virtio_console.c, branch v4.9 Linux kernel source tree virtio: console: Unlock vqs while freeing buffers 2016-10-30T22:21:44+00:00 Matt Redfearn matt.redfearn@imgtec.com 2016-10-11T11:05:15+00:00 34563769e438d2881f62cf4d9badc4e589ac0ec0 Commit c6017e793b93 ("virtio: console: add locks around buffer removal in port unplug path") added locking around the freeing of buffers in the vq. However, when free_buf() is called with can_sleep = true and rproc is enabled, it calls dma_free_coherent() directly, requiring interrupts to be enabled. Currently a WARNING is triggered due to the spin locking around free_buf, with a call stack like this: WARNING: CPU: 3 PID: 121 at ./include/linux/dma-mapping.h:433 free_buf+0x1a8/0x288 Call Trace: [<8040c538>] show_stack+0x74/0xc0 [<80757240>] dump_stack+0xd0/0x110 [<80430d98>] __warn+0xfc/0x130 [<80430ee0>] warn_slowpath_null+0x2c/0x3c [<807e7c6c>] free_buf+0x1a8/0x288 [<807ea590>] remove_port_data+0x50/0xac [<807ea6a0>] unplug_port+0xb4/0x1bc [<807ea858>] virtcons_remove+0xb0/0xfc [<807b6734>] virtio_dev_remove+0x58/0xc0 [<807f918c>] __device_release_driver+0xac/0x134 [<807f924c>] device_release_driver+0x38/0x50 [<807f7edc>] bus_remove_device+0xfc/0x130 [<807f4b74>] device_del+0x17c/0x21c [<807f4c38>] device_unregister+0x24/0x38 [<807b6b50>] unregister_virtio_device+0x28/0x44 Fix this by restructuring the loops to allow the locks to only be taken where it is necessary to protect the vqs, and release it while the buffer is being freed. Fixes: c6017e793b93 ("virtio: console: add locks around buffer removal in port unplug path") Cc: stable@vger.kernel.org Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> 
Commit c6017e793b93 ("virtio: console: add locks around buffer removal
in port unplug path") added locking around the freeing of buffers in the
vq. However, when free_buf() is called with can_sleep = true and rproc
is enabled, it calls dma_free_coherent() directly, requiring interrupts
to be enabled. Currently a WARNING is triggered due to the spin locking
around free_buf, with a call stack like this:

WARNING: CPU: 3 PID: 121 at ./include/linux/dma-mapping.h:433
free_buf+0x1a8/0x288
Call Trace:
[<8040c538>] show_stack+0x74/0xc0
[<80757240>] dump_stack+0xd0/0x110
[<80430d98>] __warn+0xfc/0x130
[<80430ee0>] warn_slowpath_null+0x2c/0x3c
[<807e7c6c>] free_buf+0x1a8/0x288
[<807ea590>] remove_port_data+0x50/0xac
[<807ea6a0>] unplug_port+0xb4/0x1bc
[<807ea858>] virtcons_remove+0xb0/0xfc
[<807b6734>] virtio_dev_remove+0x58/0xc0
[<807f918c>] __device_release_driver+0xac/0x134
[<807f924c>] device_release_driver+0x38/0x50
[<807f7edc>] bus_remove_device+0xfc/0x130
[<807f4b74>] device_del+0x17c/0x21c
[<807f4c38>] device_unregister+0x24/0x38
[<807b6b50>] unregister_virtio_device+0x28/0x44

Fix this by restructuring the loops to allow the locks to only be taken
where it is necessary to protect the vqs, and release it while the
buffer is being freed.

Fixes: c6017e793b93 ("virtio: console: add locks around buffer removal in port unplug path")
Cc: stable@vger.kernel.org
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
treewide: remove redundant #include <linux/kconfig.h> 2016-10-11T22:06:33+00:00 Masahiro Yamada yamada.masahiro@socionext.com 2016-10-11T20:55:58+00:00 97139d4a6f26445de47b378cddd5192c0278f863 Kernel source files need not include <linux/kconfig.h> explicitly because the top Makefile forces to include it with: -include $(srctree)/include/linux/kconfig.h This commit removes explicit includes except the following: * arch/s390/include/asm/facilities_src.h * tools/testing/radix-tree/linux/kernel.h These two are used for host programs. Link: http://lkml.kernel.org/r/1473656164-11929-1-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Kernel source files need not include <linux/kconfig.h> explicitly
because the top Makefile forces to include it with:

  -include $(srctree)/include/linux/kconfig.h

This commit removes explicit includes except the following:

  * arch/s390/include/asm/facilities_src.h
  * tools/testing/radix-tree/linux/kernel.h

These two are used for host programs.

Link: http://lkml.kernel.org/r/1473656164-11929-1-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
pipe: add pipe_buf_steal() helper 2016-10-05T22:23:59+00:00 Miklos Szeredi mszeredi@redhat.com 2016-09-27T08:45:12+00:00 ca76f5b6bdbdc50af0d7b98cfcf7a2be7e95eb3d Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
virtio_console: Stop doing DMA on the stack 2016-09-09T18:12:45+00:00 Andy Lutomirski luto@kernel.org 2016-08-30T15:04:15+00:00 5e59d9a1aed26abcc79abe78af5cfd34e53cbe7f virtio_console uses a small DMA buffer for control requests. Move that buffer into heap memory. Doing virtio DMA on the stack is normally okay on non-DMA-API virtio systems (which is currently most of them), but it breaks completely if the stack is virtually mapped. Tested by typing both directions using picocom aimed at /dev/hvc0. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> 
virtio_console uses a small DMA buffer for control requests.  Move
that buffer into heap memory.

Doing virtio DMA on the stack is normally okay on non-DMA-API virtio
systems (which is currently most of them), but it breaks completely
if the stack is virtually mapped.

Tested by typing both directions using picocom aimed at /dev/hvc0.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
virtio_console: silence a static checker warning 2015-05-24T19:24:35+00:00 Dan Carpenter dan.carpenter@oracle.com 2015-05-08T09:16:25+00:00 db1700685c0ad2ecb9e42af6a568435a03bbc3fd My static checker complains that this sprintf() can overflow but really it can't. Just silence the warning by using snprintf(). Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
My static checker complains that this sprintf() can overflow but really
it can't.  Just silence the warning by using snprintf().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio_console: Use bool function return values of true/false not 1/0 2015-04-03T14:15:30+00:00 Joe Perches joe@perches.com 2015-03-30T23:46:10+00:00 f580d730c90c11be0ef4fe88aff3de80845176cb Use the normal return values for bool functions Signed-off-by: Joe Perches <joe@perches.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Use the normal return values for bool functions

Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio_console: avoid config access from irq 2015-03-05T03:06:18+00:00 Michael S. Tsirkin mst@redhat.com 2015-03-05T00:15:49+00:00 eeb8a7e8bb123e84daeef84f5a2eab99ad2839a2 when multiport is off, virtio console invokes config access from irq context, config access is blocking on s390. Fix this up by scheduling work from config irq - similar to what we do for multiport configs. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org 
when multiport is off, virtio console invokes config access from irq
context, config access is blocking on s390.
Fix this up by scheduling work from config irq - similar to what we do
for multiport configs.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
virtio_console: init work unconditionally 2015-03-05T03:06:17+00:00 Michael S. Tsirkin mst@redhat.com 2015-03-05T00:15:30+00:00 4f6e24ed9de8634d6471ef86b382cba6d4e57ca8 when multiport is off, we don't initialize config work, but we then cancel uninitialized control_work on freeze. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org 
when multiport is off, we don't initialize config work,
but we then cancel uninitialized control_work on freeze.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
virtio: don't require a config space on the console device. 2015-02-11T04:33:17+00:00 Rusty Russell rusty@rustcorp.com.au 2015-02-11T04:31:14+00:00 be8ff5952a8d943660d3c01f1abf4e71eb565fdb Strictly, it's only needed when we have features (size or multiport). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> 
Strictly, it's only needed when we have features (size or multiport).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
virtio/console: verify device has config space 2015-01-21T05:58:46+00:00 Michael S. Tsirkin mst@redhat.com 2015-01-12T14:23:37+00:00 011f0e7a6944855436fb29c7a7e6c3c89c95f8fb Some devices might not implement config space access (e.g. remoteproc used not to - before 3.9). virtio/console needs config space access so make it fail gracefully if not there. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> 
Some devices might not implement config space access
(e.g. remoteproc used not to - before 3.9).
virtio/console needs config space access so make it
fail gracefully if not there.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>