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Michael J. Ruhl 6763372b81 IB/hfi1: Eliminate races in the SDMA send error path 
commit a0e0cb8280 upstream.

pq_update() can only be called in two places: from the completion
function when the complete (npkts) sequence of packets has been
submitted and processed, or from setup function if a subset of the
packets were submitted (i.e. the error path).

Currently both paths can call pq_update() if an error occurrs.  This
race will cause the n_req value to go negative, hanging file_close(),
or cause a crash by freeing the txlist more than once.

Several variables are used to determine SDMA send state.  Most of
these are unnecessary, and have code inspectible races between the
setup function and the completion function, in both the send path and
the error path.

The request 'status' value can be set by the setup or by the
completion function.  This is code inspectibly racy.  Since the status
is not needed in the completion code or by the caller it has been
removed.

The request 'done' value races between usage by the setup and the
completion function.  The completion function does not need this.
When the number of processed packets matches npkts, it is done.

The 'has_error' value races between usage of the setup and the
completion function.  This can cause incorrect error handling and leave
the n_req in an incorrect value (i.e. negative).

Simplify the code by removing all of the unneeded state checks and
variables.

Clean up iovs node when it is freed.

Eliminate race conditions in the error path:

If all packets are submitted, the completion handler will set the
completion status correctly (ok or aborted).

If all packets are not submitted, the caller must wait until the
submitted packets have completed, and then set the completion status.

These two change eliminate the race condition in the error path.

Reviewed-by: Mitko Haralanov <mitko.haralanov@intel.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2018-12-01 09:37:30 +01:00
arch RISC-V: Fix raw_copy_{to,from}_user() 2018-11-27 16:13:08 +01:00
block block: Clear kernel memory before copying to user 2018-11-27 16:13:05 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: user - fix leaking uninitialized memory to userspace 2018-11-21 09:19:24 +01:00
Documentation can: hi311x: Use level-triggered interrupt 2018-12-01 09:37:30 +01:00
drivers IB/hfi1: Eliminate races in the SDMA send error path 2018-12-01 09:37:30 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs gfs2: Don't leave s_fs_info pointing to freed memory in init_sbd 2018-12-01 09:37:27 +01:00
include can: rx-offload: rename can_rx_offload_irq_queue_err_skb() to can_rx_offload_queue_tail() 2018-12-01 09:37:29 +01:00
init Kbuild updates for v4.19 (2nd) 2018-08-25 13:40:38 -07:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel sched/core: Take the hotplug lock in sched_init_smp() 2018-11-27 16:13:06 +01:00
lib lib/raid6: Fix arm64 test build 2018-11-27 16:13:05 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/memory.c: recheck page table entry with page table lock held 2018-12-01 09:37:28 +01:00
net can: raw: check for CAN FD capable netdev in raw_sendmsg() 2018-12-01 09:37:30 +01:00
samples samples: disable CONFIG_SAMPLES for UML 2018-10-11 02:15:46 +09:00
scripts Revert "scripts/setlocalversion: git: Make -dirty check more robust" 2018-11-27 16:13:08 +01:00
security selinux: Add __GFP_NOWARN to allocation at str_read() 2018-12-01 09:37:27 +01:00
sound ALSA: oss: Use kvzalloc() for local buffer allocations 2018-12-01 09:37:25 +01:00
tools tools/power/cpupower: fix compilation with STATIC=true 2018-12-01 09:37:27 +01:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: arm64: Fix caching of host MDCR_EL2 value 2018-11-13 11:08:47 -08:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:37:25 +01:00
Makefile Linux 4.19.5 2018-11-27 16:13:11 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.