From 0437884e2dd1d321f366c14999ca49c1b74b7286 Mon Sep 17 00:00:00 2001 From: "stefan.nickl@gmail.com" Date: Tue, 14 May 2019 19:31:26 +0200 Subject: [PATCH] package/musl: Make scheduler functions Linux-compatible The POSIX functions sched_getscheduler(), sched_setscheduler(), sched_getparam(), sched_setparam() are technically not correctly implemented by the Linux syscalls of the same name, because what the kernel calls a PID and what POSIX calls a PID isn't truly the same, resulting in somewhat different semantics as to what these functions exactly apply to. Details: https://sourceware.org/bugzilla/show_bug.cgi?id=14829 Since the musl developers put a high premium on POSIX compliance, they deliberately implement these functions to return -ENOSYS instead of relaying them to the respective Linux syscalls as glibc/uClibc do. Unfortunally this breaks virtually all Linux programs using these functions under musl. For example running 'chrt -p 1' fails with 'Function not implemented' on a musl-libc based system. In particular, it affects embedded systems using these interfaces for scheduling real-time processes. As it seems unfeasible to fix all affected programs to manually use syscall wrappers instead of the libc functions, make musl behave the Linux way. Signed-off-by: Stefan Nickl Reviewed-by: Arnout Vandecappelle (Essensium/Mind) Signed-off-by: Arnout Vandecappelle (Essensium/Mind) --- ...e-scheduler-functions-Linux-compatib.patch | 76 +++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 package/musl/0002-package-musl-Make-scheduler-functions-Linux-compatib.patch diff --git a/package/musl/0002-package-musl-Make-scheduler-functions-Linux-compatib.patch b/package/musl/0002-package-musl-Make-scheduler-functions-Linux-compatib.patch new file mode 100644 index 0000000000..7c3acf9f02 --- /dev/null +++ b/package/musl/0002-package-musl-Make-scheduler-functions-Linux-compatib.patch @@ -0,0 +1,76 @@ +From 407c96fc790d0d11ca9603a2a533216c745b5051 Mon Sep 17 00:00:00 2001 +From: Stefan Nickl +Date: Mon, 13 May 2019 22:33:21 +0200 +Subject: [PATCH] Make scheduler functions Linux-compatible + +Let sched_getscheduler(), sched_setscheduler(), sched_getparam(), +sched_setparam() invoke the Linux syscalls of the same name instead +of returning -ENOSYS. + +Signed-off-by: Stefan Nickl +--- + src/sched/sched_getparam.c | 3 +-- + src/sched/sched_getscheduler.c | 3 +-- + src/sched/sched_setparam.c | 3 +-- + src/sched/sched_setscheduler.c | 3 +-- + 4 files changed, 4 insertions(+), 8 deletions(-) + +diff --git a/src/sched/sched_getparam.c b/src/sched/sched_getparam.c +index 76f10e4..65be107 100644 +--- a/src/sched/sched_getparam.c ++++ b/src/sched/sched_getparam.c +@@ -1,8 +1,7 @@ + #include +-#include + #include "syscall.h" + + int sched_getparam(pid_t pid, struct sched_param *param) + { +- return __syscall_ret(-ENOSYS); ++ return syscall(SYS_sched_getparam, pid, param); + } +diff --git a/src/sched/sched_getscheduler.c b/src/sched/sched_getscheduler.c +index 394e508..4c922f6 100644 +--- a/src/sched/sched_getscheduler.c ++++ b/src/sched/sched_getscheduler.c +@@ -1,8 +1,7 @@ + #include +-#include + #include "syscall.h" + + int sched_getscheduler(pid_t pid) + { +- return __syscall_ret(-ENOSYS); ++ return syscall(SYS_sched_getscheduler, pid); + } +diff --git a/src/sched/sched_setparam.c b/src/sched/sched_setparam.c +index 18623ee..f699faf 100644 +--- a/src/sched/sched_setparam.c ++++ b/src/sched/sched_setparam.c +@@ -1,8 +1,7 @@ + #include +-#include + #include "syscall.h" + + int sched_setparam(pid_t pid, const struct sched_param *param) + { +- return __syscall_ret(-ENOSYS); ++ return syscall(SYS_sched_setparam, pid, param); + } +diff --git a/src/sched/sched_setscheduler.c b/src/sched/sched_setscheduler.c +index 4435f21..e678221 100644 +--- a/src/sched/sched_setscheduler.c ++++ b/src/sched/sched_setscheduler.c +@@ -1,8 +1,7 @@ + #include +-#include + #include "syscall.h" + + int sched_setscheduler(pid_t pid, int sched, const struct sched_param *param) + { +- return __syscall_ret(-ENOSYS); ++ return syscall(SYS_sched_setscheduler, pid, sched, param); + } +-- +2.21.0 + -- 2.30.2