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Linux kernel for uConsole
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Masami Hiramatsu dee3f77032 tracing: Lock event_mutex before synth_event_mutex 
[ Upstream commit fc800a10be ]

synthetic event is using synth_event_mutex for protecting
synth_event_list, and event_trigger_write() path acquires
locks as below order.

event_trigger_write(event_mutex)
  ->trigger_process_regex(trigger_cmd_mutex)
    ->event_hist_trigger_func(synth_event_mutex)

On the other hand, synthetic event creation and deletion paths
call trace_add_event_call() and trace_remove_event_call()
which acquires event_mutex. In that case, if we keep the
synth_event_mutex locked while registering/unregistering synthetic
events, its dependency will be inversed.

To avoid this issue, current synthetic event is using a 2 phase
process to create/delete events. For example, it searches existing
events under synth_event_mutex to check for event-name conflicts, and
unlocks synth_event_mutex, then registers a new event under event_mutex
locked. Finally, it locks synth_event_mutex and tries to add the
new event to the list. But it can introduce complexity and a chance
for name conflicts.

To solve this simpler, this introduces trace_add_event_call_nolock()
and trace_remove_event_call_nolock() which don't acquire
event_mutex inside. synthetic event can lock event_mutex before
synth_event_mutex to solve the lock dependency issue simpler.

Link: http://lkml.kernel.org/r/154140844377.17322.13781091165954002713.stgit@devbox

Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-12-05 09:19:49 +01:00
arch ARM: dts: Fix up SQ201 flash access 2019-12-05 09:19:48 +01:00
block block: call rq_qos_exit() after queue is frozen 2019-12-01 09:17:06 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: testmgr - fix sizeof() on COMP_BUF_SIZE 2019-12-01 09:16:13 +01:00
Documentation x86/speculation: Fix incorrect MDS/TAA mitigation status 2019-12-01 09:17:37 +01:00
drivers scsi: lpfc: Fix dif and first burst use in write commands 2019-12-05 09:19:48 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs ceph: return -EINVAL if given fsc mount option on kernel w/o support 2019-12-05 09:19:45 +01:00
include tracing: Lock event_mutex before synth_event_mutex 2019-12-05 09:19:49 +01:00
init initramfs: don't free a non-existent initrd 2019-10-01 08:26:09 +02:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel tracing: Lock event_mutex before synth_event_mutex 2019-12-05 09:19:49 +01:00
lib idr: Fix idr_alloc_u32 on 32-bit systems 2019-12-05 09:19:40 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/memory_hotplug: don't access uninitialized memmaps in shrink_zone_span() 2019-12-01 09:17:36 +01:00
net mac80211: fix station inactive_time shortly after boot 2019-12-05 09:19:46 +01:00
samples samples/bpf: fix build by setting HAVE_ATTR_TEST to zero 2019-12-05 09:19:39 +01:00
scripts scripts/gdb: fix debugging modules compiled with hot/cold partitioning 2019-12-05 09:19:44 +01:00
security ima: fix freeing ongoing ahash_request 2019-10-11 18:21:11 +02:00
sound ASoC: stm32: sai: add restriction on mmap support 2019-12-05 09:19:44 +01:00
tools usbip: tools: fix fd leakage in the function of read_attr_usbip_status 2019-12-01 09:17:40 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved 2019-12-01 09:17:35 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.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 USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.87 2019-12-01 09:17:47 +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.