License cleanup: add SPDX GPL-2.0 license identifier to files with no license
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 <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
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/* SPDX-License-Identifier: GPL-2.0 */
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2005-04-16 22:20:36 +00:00
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#ifndef _LINUX_PIPE_FS_I_H
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#define _LINUX_PIPE_FS_I_H
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2010-05-20 08:43:18 +00:00
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#define PIPE_DEF_BUFFERS 16
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2005-04-16 22:20:36 +00:00
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2006-05-03 08:35:26 +00:00
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#define PIPE_BUF_FLAG_LRU 0x01 /* page is on the LRU */
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#define PIPE_BUF_FLAG_ATOMIC 0x02 /* was atomically mapped */
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#define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */
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pipes: add a "packetized pipe" mode for writing
The actual internal pipe implementation is already really about
individual packets (called "pipe buffers"), and this simply exposes that
as a special packetized mode.
When we are in the packetized mode (marked by O_DIRECT as suggested by
Alan Cox), a write() on a pipe will not merge the new data with previous
writes, so each write will get a pipe buffer of its own. The pipe
buffer is then marked with the PIPE_BUF_FLAG_PACKET flag, which in turn
will tell the reader side to break the read at that boundary (and throw
away any partial packet contents that do not fit in the read buffer).
End result: as long as you do writes less than PIPE_BUF in size (so that
the pipe doesn't have to split them up), you can now treat the pipe as a
packet interface, where each read() system call will read one packet at
a time. You can just use a sufficiently big read buffer (PIPE_BUF is
sufficient, since bigger than that doesn't guarantee atomicity anyway),
and the return value of the read() will naturally give you the size of
the packet.
NOTE! We do not support zero-sized packets, and zero-sized reads and
writes to a pipe continue to be no-ops. Also note that big packets will
currently be split at write time, but that the size at which that
happens is not really specified (except that it's bigger than PIPE_BUF).
Currently that limit is the system page size, but we might want to
explicitly support bigger packets some day.
The main user for this is going to be the autofs packet interface,
allowing us to stop having to care so deeply about exact packet sizes
(which have had bugs with 32/64-bit compatibility modes). But user
space can create packetized pipes with "pipe2(fd, O_DIRECT)", which will
fail with an EINVAL on kernels that do not support this interface.
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Miller <davem@davemloft.net>
Cc: Ian Kent <raven@themaw.net>
Cc: Thomas Meyer <thomas@m3y3r.de>
Cc: stable@kernel.org # needed for systemd/autofs interaction fix
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-29 20:12:42 +00:00
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#define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */
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2006-04-02 21:11:04 +00:00
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2007-06-12 18:51:32 +00:00
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/**
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* struct pipe_buffer - a linux kernel pipe buffer
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* @page: the page containing the data for the pipe buffer
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* @offset: offset of data inside the @page
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* @len: length of data inside the @page
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* @ops: operations associated with this buffer. See @pipe_buf_operations.
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* @flags: pipe buffer flags. See above.
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* @private: private data owned by the ops.
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**/
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2005-04-16 22:20:36 +00:00
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struct pipe_buffer {
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struct page *page;
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unsigned int offset, len;
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2006-12-13 08:34:04 +00:00
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const struct pipe_buf_operations *ops;
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2006-04-02 21:11:04 +00:00
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unsigned int flags;
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2007-06-11 10:00:45 +00:00
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unsigned long private;
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2005-04-16 22:20:36 +00:00
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};
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2007-06-12 18:51:32 +00:00
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/**
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* struct pipe_inode_info - a linux kernel pipe
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2013-03-21 06:32:24 +00:00
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* @mutex: mutex protecting the whole thing
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2020-02-10 03:36:14 +00:00
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* @rd_wait: reader wait point in case of empty pipe
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* @wr_wait: writer wait point in case of full pipe
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2019-11-15 13:30:32 +00:00
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* @head: The point of buffer production
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* @tail: The point of buffer consumption
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2019-10-16 15:47:32 +00:00
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* @max_usage: The maximum number of slots that may be used in the ring
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2019-11-15 13:30:32 +00:00
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* @ring_size: total number of buffers (should be a power of 2)
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2007-06-12 18:51:32 +00:00
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* @tmp_page: cached released page
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* @readers: number of current readers of this pipe
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* @writers: number of current writers of this pipe
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2014-02-18 13:54:36 +00:00
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* @files: number of struct file referring this pipe (protected by ->i_lock)
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2007-06-12 18:51:32 +00:00
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* @r_counter: reader counter
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* @w_counter: writer counter
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* @fasync_readers: reader side fasync
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* @fasync_writers: writer side fasync
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* @bufs: the circular array of pipe buffers
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2016-01-18 15:36:09 +00:00
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* @user: the user who created this pipe
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2007-06-12 18:51:32 +00:00
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**/
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2007-06-04 13:03:12 +00:00
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struct pipe_inode_info {
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2013-03-21 06:32:24 +00:00
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struct mutex mutex;
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pipe: use exclusive waits when reading or writing
This makes the pipe code use separate wait-queues and exclusive waiting
for readers and writers, avoiding a nasty thundering herd problem when
there are lots of readers waiting for data on a pipe (or, less commonly,
lots of writers waiting for a pipe to have space).
While this isn't a common occurrence in the traditional "use a pipe as a
data transport" case, where you typically only have a single reader and
a single writer process, there is one common special case: using a pipe
as a source of "locking tokens" rather than for data communication.
In particular, the GNU make jobserver code ends up using a pipe as a way
to limit parallelism, where each job consumes a token by reading a byte
from the jobserver pipe, and releases the token by writing a byte back
to the pipe.
This pattern is fairly traditional on Unix, and works very well, but
will waste a lot of time waking up a lot of processes when only a single
reader needs to be woken up when a writer releases a new token.
A simplified test-case of just this pipe interaction is to create 64
processes, and then pass a single token around between them (this
test-case also intentionally passes another token that gets ignored to
test the "wake up next" logic too, in case anybody wonders about it):
#include <unistd.h>
int main(int argc, char **argv)
{
int fd[2], counters[2];
pipe(fd);
counters[0] = 0;
counters[1] = -1;
write(fd[1], counters, sizeof(counters));
/* 64 processes */
fork(); fork(); fork(); fork(); fork(); fork();
do {
int i;
read(fd[0], &i, sizeof(i));
if (i < 0)
continue;
counters[0] = i+1;
write(fd[1], counters, (1+(i & 1)) *sizeof(int));
} while (counters[0] < 1000000);
return 0;
}
and in a perfect world, passing that token around should only cause one
context switch per transfer, when the writer of a token causes a
directed wakeup of just a single reader.
But with the "writer wakes all readers" model we traditionally had, on
my test box the above case causes more than an order of magnitude more
scheduling: instead of the expected ~1M context switches, "perf stat"
shows
231,852.37 msec task-clock # 15.857 CPUs utilized
11,250,961 context-switches # 0.049 M/sec
616,304 cpu-migrations # 0.003 M/sec
1,648 page-faults # 0.007 K/sec
1,097,903,998,514 cycles # 4.735 GHz
120,781,778,352 instructions # 0.11 insn per cycle
27,997,056,043 branches # 120.754 M/sec
283,581,233 branch-misses # 1.01% of all branches
14.621273891 seconds time elapsed
0.018243000 seconds user
3.611468000 seconds sys
before this commit.
After this commit, I get
5,229.55 msec task-clock # 3.072 CPUs utilized
1,212,233 context-switches # 0.232 M/sec
103,951 cpu-migrations # 0.020 M/sec
1,328 page-faults # 0.254 K/sec
21,307,456,166 cycles # 4.074 GHz
12,947,819,999 instructions # 0.61 insn per cycle
2,881,985,678 branches # 551.096 M/sec
64,267,015 branch-misses # 2.23% of all branches
1.702148350 seconds time elapsed
0.004868000 seconds user
0.110786000 seconds sys
instead. Much better.
[ Note! This kernel improvement seems to be very good at triggering a
race condition in the make jobserver (in GNU make 4.2.1) for me. It's
a long known bug that was fixed back in June 2017 by GNU make commit
b552b0525198 ("[SV 51159] Use a non-blocking read with pselect to
avoid hangs.").
But there wasn't a new release of GNU make until 4.3 on Jan 19 2020,
so a number of distributions may still have the buggy version. Some
have backported the fix to their 4.2.1 release, though, and even
without the fix it's quite timing-dependent whether the bug actually
is hit. ]
Josh Triplett says:
"I've been hammering on your pipe fix patch (switching to exclusive
wait queues) for a month or so, on several different systems, and I've
run into no issues with it. The patch *substantially* improves
parallel build times on large (~100 CPU) systems, both with parallel
make and with other things that use make's pipe-based jobserver.
All current distributions (including stable and long-term stable
distributions) have versions of GNU make that no longer have the
jobserver bug"
Tested-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-09 17:48:27 +00:00
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wait_queue_head_t rd_wait, wr_wait;
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2019-11-15 13:30:32 +00:00
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unsigned int head;
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unsigned int tail;
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2019-10-16 15:47:32 +00:00
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unsigned int max_usage;
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2019-11-15 13:30:32 +00:00
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unsigned int ring_size;
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2007-06-04 13:03:12 +00:00
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unsigned int readers;
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unsigned int writers;
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2013-03-21 06:21:19 +00:00
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unsigned int files;
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2007-06-04 13:03:12 +00:00
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unsigned int r_counter;
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unsigned int w_counter;
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2010-05-20 08:43:18 +00:00
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struct page *tmp_page;
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2007-06-04 13:03:12 +00:00
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struct fasync_struct *fasync_readers;
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struct fasync_struct *fasync_writers;
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2010-05-20 08:43:18 +00:00
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struct pipe_buffer *bufs;
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2016-01-18 15:36:09 +00:00
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struct user_struct *user;
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2007-06-04 13:03:12 +00:00
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};
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2006-05-01 17:59:03 +00:00
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/*
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* Note on the nesting of these functions:
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*
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2007-06-14 11:10:48 +00:00
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* ->confirm()
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2006-05-01 17:59:03 +00:00
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* ->steal()
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*
|
2016-09-27 08:45:13 +00:00
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* That is, ->steal() must be called on a confirmed buffer.
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* See below for the meaning of each operation. Also see kerneldoc
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* in fs/pipe.c for the pipe and generic variants of these hooks.
|
2006-05-01 17:59:03 +00:00
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*/
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2005-04-16 22:20:36 +00:00
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struct pipe_buf_operations {
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2007-06-12 18:51:32 +00:00
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/*
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* ->confirm() verifies that the data in the pipe buffer is there
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* and that the contents are good. If the pages in the pipe belong
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* to a file system, we may need to wait for IO completion in this
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* hook. Returns 0 for good, or a negative error value in case of
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* error.
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*/
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2007-06-14 11:10:48 +00:00
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int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
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2007-06-12 18:51:32 +00:00
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/*
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* When the contents of this pipe buffer has been completely
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* consumed by a reader, ->release() is called.
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*/
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2005-04-16 22:20:36 +00:00
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void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
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2007-06-12 18:51:32 +00:00
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/*
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* Attempt to take ownership of the pipe buffer and its contents.
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* ->steal() returns 0 for success, in which case the contents
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* of the pipe (the buf->page) is locked and now completely owned
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* by the caller. The page may then be transferred to a different
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* mapping, the most often used case is insertion into different
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* file address space cache.
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*/
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2006-03-30 13:16:46 +00:00
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int (*steal)(struct pipe_inode_info *, struct pipe_buffer *);
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2007-06-12 18:51:32 +00:00
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/*
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* Get a reference to the pipe buffer.
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*/
|
2019-04-05 21:02:10 +00:00
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bool (*get)(struct pipe_inode_info *, struct pipe_buffer *);
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2005-04-16 22:20:36 +00:00
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};
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2019-11-15 13:30:32 +00:00
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/**
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* pipe_empty - Return true if the pipe is empty
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* @head: The pipe ring head pointer
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* @tail: The pipe ring tail pointer
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*/
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static inline bool pipe_empty(unsigned int head, unsigned int tail)
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{
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return head == tail;
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}
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/**
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* pipe_occupancy - Return number of slots used in the pipe
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* @head: The pipe ring head pointer
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* @tail: The pipe ring tail pointer
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*/
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static inline unsigned int pipe_occupancy(unsigned int head, unsigned int tail)
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{
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return head - tail;
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}
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/**
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* pipe_full - Return true if the pipe is full
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* @head: The pipe ring head pointer
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* @tail: The pipe ring tail pointer
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* @limit: The maximum amount of slots available.
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*/
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static inline bool pipe_full(unsigned int head, unsigned int tail,
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unsigned int limit)
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{
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return pipe_occupancy(head, tail) >= limit;
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}
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/**
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* pipe_space_for_user - Return number of slots available to userspace
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* @head: The pipe ring head pointer
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* @tail: The pipe ring tail pointer
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* @pipe: The pipe info structure
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*/
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static inline unsigned int pipe_space_for_user(unsigned int head, unsigned int tail,
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struct pipe_inode_info *pipe)
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{
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unsigned int p_occupancy, p_space;
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p_occupancy = pipe_occupancy(head, tail);
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2019-10-16 15:47:32 +00:00
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if (p_occupancy >= pipe->max_usage)
|
2019-11-15 13:30:32 +00:00
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return 0;
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p_space = pipe->ring_size - p_occupancy;
|
2019-10-16 15:47:32 +00:00
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if (p_space > pipe->max_usage)
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p_space = pipe->max_usage;
|
2019-11-15 13:30:32 +00:00
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return p_space;
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}
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2016-09-27 08:45:12 +00:00
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/**
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* pipe_buf_get - get a reference to a pipe_buffer
|
|
|
|
* @pipe: the pipe that the buffer belongs to
|
|
|
|
* @buf: the buffer to get a reference to
|
2019-04-05 21:02:10 +00:00
|
|
|
*
|
|
|
|
* Return: %true if the reference was successfully obtained.
|
2016-09-27 08:45:12 +00:00
|
|
|
*/
|
2019-04-05 21:02:10 +00:00
|
|
|
static inline __must_check bool pipe_buf_get(struct pipe_inode_info *pipe,
|
2016-09-27 08:45:12 +00:00
|
|
|
struct pipe_buffer *buf)
|
|
|
|
{
|
2019-04-05 21:02:10 +00:00
|
|
|
return buf->ops->get(pipe, buf);
|
2016-09-27 08:45:12 +00:00
|
|
|
}
|
|
|
|
|
2016-09-27 08:45:12 +00:00
|
|
|
/**
|
|
|
|
* pipe_buf_release - put a reference to a pipe_buffer
|
|
|
|
* @pipe: the pipe that the buffer belongs to
|
|
|
|
* @buf: the buffer to put a reference to
|
|
|
|
*/
|
|
|
|
static inline void pipe_buf_release(struct pipe_inode_info *pipe,
|
|
|
|
struct pipe_buffer *buf)
|
|
|
|
{
|
|
|
|
const struct pipe_buf_operations *ops = buf->ops;
|
|
|
|
|
|
|
|
buf->ops = NULL;
|
|
|
|
ops->release(pipe, buf);
|
|
|
|
}
|
|
|
|
|
2016-09-27 08:45:12 +00:00
|
|
|
/**
|
|
|
|
* pipe_buf_confirm - verify contents of the pipe buffer
|
|
|
|
* @pipe: the pipe that the buffer belongs to
|
|
|
|
* @buf: the buffer to confirm
|
|
|
|
*/
|
|
|
|
static inline int pipe_buf_confirm(struct pipe_inode_info *pipe,
|
|
|
|
struct pipe_buffer *buf)
|
|
|
|
{
|
|
|
|
return buf->ops->confirm(pipe, buf);
|
|
|
|
}
|
|
|
|
|
2016-09-27 08:45:12 +00:00
|
|
|
/**
|
|
|
|
* pipe_buf_steal - attempt to take ownership of a pipe_buffer
|
|
|
|
* @pipe: the pipe that the buffer belongs to
|
|
|
|
* @buf: the buffer to attempt to steal
|
|
|
|
*/
|
|
|
|
static inline int pipe_buf_steal(struct pipe_inode_info *pipe,
|
|
|
|
struct pipe_buffer *buf)
|
|
|
|
{
|
|
|
|
return buf->ops->steal(pipe, buf);
|
|
|
|
}
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
|
|
|
|
memory allocation, whereas PIPE_BUF makes atomicity guarantees. */
|
|
|
|
#define PIPE_SIZE PAGE_SIZE
|
|
|
|
|
2009-04-14 17:48:41 +00:00
|
|
|
/* Pipe lock and unlock operations */
|
|
|
|
void pipe_lock(struct pipe_inode_info *);
|
|
|
|
void pipe_unlock(struct pipe_inode_info *);
|
|
|
|
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
|
|
|
|
|
2018-02-06 23:41:45 +00:00
|
|
|
extern unsigned int pipe_max_size;
|
2016-01-18 15:36:09 +00:00
|
|
|
extern unsigned long pipe_user_pages_hard;
|
|
|
|
extern unsigned long pipe_user_pages_soft;
|
2010-06-03 12:54:39 +00:00
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/* Drop the inode semaphore and wait for a pipe event, atomically */
|
2006-04-10 13:18:35 +00:00
|
|
|
void pipe_wait(struct pipe_inode_info *pipe);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2013-03-21 15:04:15 +00:00
|
|
|
struct pipe_inode_info *alloc_pipe_info(void);
|
2013-03-21 15:06:46 +00:00
|
|
|
void free_pipe_info(struct pipe_inode_info *);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2006-05-01 17:59:03 +00:00
|
|
|
/* Generic pipe buffer ops functions */
|
2019-04-05 21:02:10 +00:00
|
|
|
bool generic_pipe_buf_get(struct pipe_inode_info *, struct pipe_buffer *);
|
2007-06-14 11:10:48 +00:00
|
|
|
int generic_pipe_buf_confirm(struct pipe_inode_info *, struct pipe_buffer *);
|
2006-05-02 13:29:57 +00:00
|
|
|
int generic_pipe_buf_steal(struct pipe_inode_info *, struct pipe_buffer *);
|
2019-04-04 21:59:25 +00:00
|
|
|
int generic_pipe_buf_nosteal(struct pipe_inode_info *, struct pipe_buffer *);
|
2009-05-07 13:37:36 +00:00
|
|
|
void generic_pipe_buf_release(struct pipe_inode_info *, struct pipe_buffer *);
|
splice: don't merge into linked buffers
Before this patch, it was possible for two pipes to affect each other after
data had been transferred between them with tee():
============
$ cat tee_test.c
int main(void) {
int pipe_a[2];
if (pipe(pipe_a)) err(1, "pipe");
int pipe_b[2];
if (pipe(pipe_b)) err(1, "pipe");
if (write(pipe_a[1], "abcd", 4) != 4) err(1, "write");
if (tee(pipe_a[0], pipe_b[1], 2, 0) != 2) err(1, "tee");
if (write(pipe_b[1], "xx", 2) != 2) err(1, "write");
char buf[5];
if (read(pipe_a[0], buf, 4) != 4) err(1, "read");
buf[4] = 0;
printf("got back: '%s'\n", buf);
}
$ gcc -o tee_test tee_test.c
$ ./tee_test
got back: 'abxx'
$
============
As suggested by Al Viro, fix it by creating a separate type for
non-mergeable pipe buffers, then changing the types of buffers in
splice_pipe_to_pipe() and link_pipe().
Cc: <stable@vger.kernel.org>
Fixes: 7c77f0b3f920 ("splice: implement pipe to pipe splicing")
Fixes: 70524490ee2e ("[PATCH] splice: add support for sys_tee()")
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-01-23 14:19:17 +00:00
|
|
|
void pipe_buf_mark_unmergeable(struct pipe_buffer *buf);
|
2006-05-01 17:59:03 +00:00
|
|
|
|
2014-01-22 18:36:57 +00:00
|
|
|
extern const struct pipe_buf_operations nosteal_pipe_buf_ops;
|
|
|
|
|
2010-05-20 08:43:18 +00:00
|
|
|
/* for F_SETPIPE_SZ and F_GETPIPE_SZ */
|
|
|
|
long pipe_fcntl(struct file *, unsigned int, unsigned long arg);
|
2010-11-29 00:27:19 +00:00
|
|
|
struct pipe_inode_info *get_pipe_info(struct file *file);
|
2010-11-28 22:09:57 +00:00
|
|
|
|
2012-07-21 11:33:25 +00:00
|
|
|
int create_pipe_files(struct file **, int);
|
2018-02-06 23:42:00 +00:00
|
|
|
unsigned int round_pipe_size(unsigned long size);
|
2012-07-21 11:33:25 +00:00
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
#endif
|