16 May, 2018
1 commit
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commit 8236b0ae31c837d2b3a2565c5f8d77f637e824cc upstream.
syzbot is reporting hung tasks at wait_on_bit(WB_shutting_down) in
wb_shutdown() [1]. This seems to be because commit 5318ce7d46866e1d ("bdi:
Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") forgot to call
wake_up_bit(WB_shutting_down) after clear_bit(WB_shutting_down).Introduce a helper function clear_and_wake_up_bit() and use it, in order
to avoid similar errors in future.[1] https://syzkaller.appspot.com/bug?id=b297474817af98d5796bc544e1bb806fc3da0e5e
Signed-off-by: Tetsuo Handa
Reported-by: syzbot
Fixes: 5318ce7d46866e1d ("bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()")
Cc: Tejun Heo
Reviewed-by: Jan Kara
Suggested-by: Linus Torvalds
Signed-off-by: Jens Axboe
Signed-off-by: Greg Kroah-Hartman
02 Nov, 2017
1 commit
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
20 Jun, 2017
3 commits
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So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:struct wait_queue_head::task_list => ::head
struct wait_queue_entry::task_list => ::entryFor example, this code:
rqw->wait.task_list.next != &wait->task_list
... is was pretty unclear (to me) what it's doing, while now it's written this way:
rqw->wait.head.next != &wait->entry
... which makes it pretty clear that we are iterating a list until we see the head.
Other examples are:
list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
list_for_each_entry(wq, &fence->wait.task_list, task_list) {... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:list_for_each_entry_safe(pos, next, &x->head, entry) {
list_for_each_entry(wq, &fence->wait.head, entry) {Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
The key hashed waitqueue data structures and their initialization
was done in the main scheduler file for no good reason, move them
to sched/wait_bit.c instead.Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar -
The wait_bit*() types and APIs are mixed into wait.h, but they
are a pretty orthogonal extension of wait-queues.Furthermore, only about 50 kernel files use these APIs, while
over 1000 use the regular wait-queue functionality.So clean up the main wait.h by moving the wait-bit functionality
out of it, into a separate .h and .c file:include/linux/wait_bit.h for types and APIs
kernel/sched/wait_bit.c for the implementationUpdate all header dependencies.
This reduces the size of wait.h rather significantly, by about 30%.
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
