path: root/src/stdio/fgetln.c
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authorRich Felker <>2018-09-15 13:45:41 -0400
committerRich Felker <>2018-09-15 14:22:06 -0400
commit5994de4e02a05c19a6bddadcfb687ab2e7511bd6 (patch)
tree5d0ffa57b7a59fdc6323afd105fcdf748f636776 /src/stdio/fgetln.c
parentdbcfb16e43af28ba919f651c51d7a2f15af656a1 (diff)
check for kernel support before allowing robust mutex creation
on some archs, linux support for futex operations (including robust_list processing) that depend on kernelspace CAS is conditional on a runtime check. as of linux 4.18, this check fails unconditionally on nommu archs that perform it, and spurious failure on powerpc64 was observed but not explained. it's also possible that futex support is omitted entirely, or that the kernel is older than 2.6.17. for most futex ops, ENOSYS does not yield hard breakage; userspace will just spin at 100% cpu load. but for robust mutexes, correct behavior depends on the kernel functionality. use the get_robust_list syscall to probe for support at the first call to pthread_mutexattr_setrobust, and block creation of robust mutexes with a reportable error if they can't be supported.
Diffstat (limited to 'src/stdio/fgetln.c')
0 files changed, 0 insertions, 0 deletions