Buildresult: linus/x86_64-allnoconfig/x86_64-gcc8 built on Mar 5 2019, 14:22

kisskb

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Status:	OK
Date/Time:	Mar 5 2019, 14:22
Duration:	0:00:25.418862
Builder:	ka2
Revision:	fs: Make splice() and tee() take into account O_NONBLOCK flag on pipes (`ee5e001196d1345b8fee25925ff5f1d67936081e)`
Target:	linus/x86_64-allnoconfig/x86_64-gcc8
Branch:	linus
Compiler:	x86_64-gcc8 (x86_64-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30)
Config:	allnoconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify ee5e001196d1345b8fee25925ff5f1d67936081e^{commit} ee5e001196d1345b8fee25925ff5f1d67936081e already have revision, skipping fetch # git checkout -q -f -B kisskb ee5e001196d1345b8fee25925ff5f1d67936081e # git clean -qxdf # < git log -1 # commit ee5e001196d1345b8fee25925ff5f1d67936081e # Author: Slavomir Kaslev <kaslevs@vmware.com> # Date: Thu Feb 7 17:45:19 2019 +0200 # # fs: Make splice() and tee() take into account O_NONBLOCK flag on pipes # # The current implementation of splice() and tee() ignores O_NONBLOCK set # on pipe file descriptors and checks only the SPLICE_F_NONBLOCK flag for # blocking on pipe arguments. This is inconsistent since splice()-ing # from/to non-pipe file descriptors does take O_NONBLOCK into # consideration. # # Fix this by promoting O_NONBLOCK, when set on a pipe, to # SPLICE_F_NONBLOCK. # # Some context for how the current implementation of splice() leads to # inconsistent behavior. In the ongoing work[1] to add VM tracing # capability to trace-cmd we stream tracing data over named FIFOs or # vsockets from guests back to the host. # # When we receive SIGINT from user to stop tracing, we set O_NONBLOCK on # the input file descriptor and set SPLICE_F_NONBLOCK for the next call to # splice(). If splice() was blocked waiting on data from the input FIFO, # after SIGINT splice() restarts with the same arguments (no # SPLICE_F_NONBLOCK) and blocks again instead of returning -EAGAIN when no # data is available. # # This differs from the splice() behavior when reading from a vsocket or # when we're doing a traditional read()/write() loop (trace-cmd's # --nosplice argument). # # With this patch applied we get the same behavior in all situations after # setting O_NONBLOCK which also matches the behavior of doing a # read()/write() loop instead of splice(). # # This change does have potential of breaking users who don't expect # EAGAIN from splice() when SPLICE_F_NONBLOCK is not set. OTOH programs # that set O_NONBLOCK and don't anticipate EAGAIN are arguably buggy[2]. # # [1] https://github.com/skaslev/trace-cmd/tree/vsock # [2] https://github.com/torvalds/linux/blob/d47e3da1759230e394096fd742aad423c291ba48/fs/read_write.c#L1425 # # Signed-off-by: Slavomir Kaslev <kaslevs@vmware.com> # Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-ld --version # < git log --format=%s --max-count=1 ee5e001196d1345b8fee25925ff5f1d67936081e # < make -s -j 8 ARCH=x86_64 O=/kisskb/build/linus_x86_64-allnoconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux- allnoconfig # make -s -j 8 ARCH=x86_64 O=/kisskb/build/linus_x86_64-allnoconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux- Completed OK # rm -rf /kisskb/build/linus_x86_64-allnoconfig_x86_64-gcc8 # Build took: 0:00:25.418862

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