# git rev-parse -q --verify ad910e36da4ca3a1bd436989f632d062dda0c921^{commit}
ad910e36da4ca3a1bd436989f632d062dda0c921
already have revision, skipping fetch
# git checkout -q -f -B kisskb ad910e36da4ca3a1bd436989f632d062dda0c921
# git clean -qxdf
# < git log -1
# commit ad910e36da4ca3a1bd436989f632d062dda0c921
# Author: Linus Torvalds <torvalds@linux-foundation.org>
# Date:   Sat Dec 7 10:41:17 2019 -0800
# 
#     pipe: fix poll/select race introduced by the pipe rework
#     
#     The kernel wait queues have a basic rule to them: you add yourself to
#     the wait-queue first, and then you check the things that you're going to
#     wait on.  That avoids the races with the event you're waiting for.
#     
#     The same goes for poll/select logic: the "poll_wait()" goes first, and
#     then you check the things you're polling for.
#     
#     Of course, if you use locking, the ordering doesn't matter since the
#     lock will serialize with anything that changes the state you're looking
#     at. That's not the case here, though.
#     
#     So move the poll_wait() first in pipe_poll(), before you start looking
#     at the pipe state.
#     
#     Fixes: 8cefc107ca54 ("pipe: Use head and tail pointers for the ring, not cursor and length")
#     Cc: David Howells <dhowells@redhat.com>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-gcc --version
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-ld --version
# < git log --format=%s --max-count=1 ad910e36da4ca3a1bd436989f632d062dda0c921
# < make -s -j 48 ARCH=arm O=/kisskb/build/linus_am200epdkit_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-  am200epdkit_defconfig
# make -s -j 48 ARCH=arm O=/kisskb/build/linus_am200epdkit_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-  
/kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl':
/kisskb/src/kernel/printk/printk.c:204:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c: In function 'proc_reg_open':
/kisskb/src/include/linux/list.h:65:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c:338:21: note: 'pdeo' was declared here
Completed OK
# rm -rf /kisskb/build/linus_am200epdkit_defconfig_arm
# Build took: 0:00:37.302789