As &vk->ctx_lock is acquired by timer bcm_vk_hb_poll() under softirq
context, other process context code should disable irq or bottom-half
before acquire the same lock, otherwise deadlock could happen if the
timer preempt the execution while the lock is held in process context
on the same CPU.
Possible deadlock scenario
bcm_vk_open()
-> bcm_vk_get_ctx()
-> spin_lock(&vk->ctx_lock)
<timer iterrupt>
-> bcm_vk_hb_poll()
-> bcm_vk_blk_drv_access()
-> spin_lock_irqsave(&vk->ctx_lock, flags) (deadlock here)
This flaw was found using an experimental static analysis tool we are
developing for irq-related deadlock, which reported the following
warning when analyzing the linux kernel 6.4-rc7 release.
[Deadlock]: &vk->ctx_lock
[Interrupt]: bcm_vk_hb_poll
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_msg.c:176
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_dev.c:512
[Locking Unit]: bcm_vk_ioctl
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_dev.c:1181
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_dev.c:512
[Deadlock]: &vk->ctx_lock
[Interrupt]: bcm_vk_hb_poll
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_msg.c:176
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_dev.c:512
[Locking Unit]: bcm_vk_ioctl
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_dev.c:1169
[Deadlock]: &vk->ctx_lock
[Interrupt]: bcm_vk_hb_poll
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_msg.c:176
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_dev.c:512
[Locking Unit]: bcm_vk_open
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_msg.c:216
[Deadlock]: &vk->ctx_lock
[Interrupt]: bcm_vk_hb_poll
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_msg.c:176
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_dev.c:512
[Locking Unit]: bcm_vk_release
-->/root/linux/drivers/misc/bcm-vk/bcm_vk_msg.c:306
As suggested by Arnd, the tentative patch fix the potential deadlocks
by replacing the timer with delay workqueue. x86_64 allyesconfig using
GCC shows no new warning. Note that no runtime testing was performed
due to no device on hand.
Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Tested-by: Desmond Yan <desmond.branden@broadcom.com>
Tested-by: Desmond Yan <desmond.yan@broadcom.com>
Link: https://lore.kernel.org/r/20230629182941.13045-1-dg573847474@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].
This code was transformed with the help of Coccinelle:
(next-20220214$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)
@@
identifier S, member, array;
type T1, T2;
@@
struct S {
...
T1 member;
T2 array[
- 0
];
};
UAPI and wireless changes were intentionally excluded from this patch
and will be sent out separately.
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
Link: https://github.com/KSPP/linux/issues/78
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Correct compile issue if CONFIG_TTY is not set by
only adding ttyVK devices if CONFIG_BCM_VK_TTY is set.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210203223826.21674-1-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add ttyVK support to driver to allow console access to VK card from host.
Device node will be in the follow form /dev/bcm-vk.x_ttyVKy where:
x is the instance of the VK card
y is the tty device number on the VK card
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-14-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add reset support via ioctl.
Kill user processes that are open when VK card is reset.
If a particular PID has issued the reset request do not kill that process
as it issued the ioctl.
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-11-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add message support in order to be able to communicate
to VK card via message queues.
This info is used for debug purposes via collection of logs via direct
read of BAR space and by sysfs access (in a follow on commit).
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-10-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add support to get card_info (details about card),
peerlog_info (to get details of peerlog on card),
and proc_mon_info (process monitoring on card).
This info is used for collection of logs via direct
read of BAR space and by sysfs access (in a follow on commit).
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-9-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add ioctl support to issue load_image operation to VK card.
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Co-developed-by: James Hu <james.hu@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: James Hu <james.hu@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-8-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add open/release to replace private data with context for other methods
to use. Reason for the context is because it is allowed for multiple
sessions to open sysfs. For each file open, when upper layer queries the
response, only those that are tied to a specified open should be returned.
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-7-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pass down an interrupt to card in case of panic or reboot so
that card can take appropriate action to perform a clean reset.
Uses kernel notifier block either directly (register on panic list),
or implicitly (add shutdown method for PCI device).
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-6-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add misc device base support to create and remove devnode.
Additional misc functions for open/read/write/release/ioctl/sysfs, etc
will be added in follow on commits to allow for individual review.
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-5-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add support to load and boot images on card automatically.
The kernel module parameter auto_load can be passed in as false to disable
such support on probe.
As well, nr_scratch_pages can be specified to allocate more or less scratch
memory on init as needed for desired card operation.
Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Co-developed-by: James Hu <james.hu@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: James Hu <james.hu@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-4-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add initial version of Broadcom VK driver to enumerate PCI device IDs
of Valkyrie and Viper device IDs.
VK based cards provide real-time high performance, high throughput,
low latency offload compute engine operations.
They are used for multiple parallel offload tasks as:
audio, video and image processing and crypto operations.
Further commits add additional features to driver beyond probe/remove.
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-3-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Chengfeng Ye