51f4f2ed3d
This is a long standing performance bug which happened to not cause trouble in practice due to rather limited use of these primitives. The read side expects the writer to finish soon(tm) hence it loops with one pause in-between. But it is possible the writer gets preempted in which case the waiting can take a long time, especially so if it got preempted by the reader. In principle this may never clean itself up. In the current kernel seq is only used to obtain stable fp + capabilities state. In order for looping at least once to occur there has to be a concurrent writer modifying the fd slot for the very fd we are trying to read. That is, for any looping to occur in the first place the program has to be multithreaded and be doing something fishy to begin with. As such, the indefinite looping is rather hard to run into unless you really try (and I did not). |
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bin | ||
cddl | ||
contrib | ||
crypto | ||
etc | ||
gnu | ||
include | ||
kerberos5 | ||
lib | ||
libexec | ||
release | ||
rescue | ||
sbin | ||
secure | ||
share | ||
stand | ||
sys | ||
targets | ||
tests | ||
tools | ||
usr.bin | ||
usr.sbin | ||
.arcconfig | ||
.arclint | ||
.gitattributes | ||
.gitignore | ||
COPYRIGHT | ||
LOCKS | ||
MAINTAINERS | ||
Makefile | ||
Makefile.inc1 | ||
Makefile.libcompat | ||
Makefile.sys.inc | ||
ObsoleteFiles.inc | ||
README | ||
README.md | ||
UPDATING |
FreeBSD Source:
This is the top level of the FreeBSD source directory. This file
was last revised on:
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The buildkernel
and installkernel
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the Makefile in this directory for more information on the
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Building a kernel is a somewhat more involved process. See build(7), config(8), and https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information.
Note: If you want to build and install the kernel with the
buildkernel
and installkernel
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