Buildresult: linus/arm64-allnoconfig/arm64-gcc5 built on Nov 27 2019, 10:14

kisskb

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Status:	OK
Date/Time:	Nov 27 2019, 10:14
Duration:	0:00:26.786792
Builder:	ka2
Revision:	Revert "vfs: properly and reliably lock f_pos in fdget_pos()" (`2be7d348fe924f0c5583c6a805bd42cecda93104)`
Target:	linus/arm64-allnoconfig/arm64-gcc5
Branch:	linus
Compiler:	arm64-gcc5 (aarch64-linux-gcc.br_real (Buildroot 2016.11-git-00613-ge98b4dd) 5.4.0 / GNU ld (GNU Binutils) 2.25.1)
Config:	allnoconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify 2be7d348fe924f0c5583c6a805bd42cecda93104^{commit} 2be7d348fe924f0c5583c6a805bd42cecda93104 already have revision, skipping fetch # git checkout -q -f -B kisskb 2be7d348fe924f0c5583c6a805bd42cecda93104 # git clean -qxdf # < git log -1 # commit 2be7d348fe924f0c5583c6a805bd42cecda93104 # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Tue Nov 26 11:34:06 2019 -0800 # # Revert "vfs: properly and reliably lock f_pos in fdget_pos()" # # This reverts commit 0be0ee71816b2b6725e2b4f32ad6726c9d729777. # # I was hoping it would be benign to switch over entirely to FMODE_STREAM, # and we'd have just a couple of small fixups we'd need, but it looks like # we're not quite there yet. # # While it worked fine on both my desktop and laptop, they are fairly # similar in other respects, and run mostly the same loads. Kenneth # Crudup reports that it seems to break both his vmware installation and # the KDE upower service. In both cases apparently leading to timeouts # due to waitinmg for the f_pos lock. # # There are a number of character devices in particular that definitely # want stream-like behavior, but that currently don't get marked as # streams, and as a result get the exclusion between concurrent # read()/write() on the same file descriptor. Which doesn't work well for # them. # # The most obvious example if this is /dev/console and /dev/tty, which use # console_fops and tty_fops respectively (and ptmx_fops for the pty master # side). It may be that it's just this that causes problems, but we # clearly weren't ready yet. # # Because there's a number of other likely common cases that don't have # llseek implementations and would seem to act as stream devices: # # /dev/fuse (fuse_dev_operations) # /dev/mcelog (mce_chrdev_ops) # /dev/mei0 (mei_fops) # /dev/net/tun (tun_fops) # /dev/nvme0 (nvme_dev_fops) # /dev/tpm0 (tpm_fops) # /proc/self/ns/mnt (ns_file_operations) # /dev/snd/pcm* (snd_pcm_f_ops[]) # # and while some of these could be trivially automatically detected by the # vfs layer when the character device is opened by just noticing that they # have no read or write operations either, it often isn't that obvious. # # Some character devices most definitely do use the file position, even if # they don't allow seeking: the firmware update code, for example, uses # simple_read_from_buffer() that does use f_pos, but doesn't allow seeking # back and forth. # # We'll revisit this when there's a better way to detect the problem and # fix it (possibly with a coccinelle script to do more of the FMODE_STREAM # annotations). # # Reported-by: Kenneth R. Crudup <kenny@panix.com> # Cc: Kirill Smelkov <kirr@nexedi.com> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-gcc --version # < /opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-ld --version # < git log --format=%s --max-count=1 2be7d348fe924f0c5583c6a805bd42cecda93104 # < make -s -j 8 ARCH=arm64 O=/kisskb/build/linus_arm64-allnoconfig_arm64-gcc5.4 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux- allnoconfig # make -s -j 8 ARCH=arm64 O=/kisskb/build/linus_arm64-allnoconfig_arm64-gcc5.4 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux- Completed OK # rm -rf /kisskb/build/linus_arm64-allnoconfig_arm64-gcc5.4 # Build took: 0:00:26.786792

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