From 89f063b900edf8b38c9dc05953887cf09b121378 Mon Sep 17 00:00:00 2001 From: Christian Eggers Date: Sun, 15 Nov 2020 20:25:09 +0100 Subject: chrt: support for musl C library musl "implements" several sched_xxx() functions by returning ENOSYS. As an alternative, either pthread_(g|s)etschedparam() or direct syscalls can be used. References: https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/schedutils/chrt.c?id=fcc3078754291d2f5121797eb91b364f8e24b2f1 References: http://git.musl-libc.org/cgit/musl/commit/src/sched/sched_setscheduler.c?id=1e21e78bf7a5c24c217446d8760be7b7188711c2 Signed-off-by: Christian Eggers Signed-off-by: Denys Vlasenko --- util-linux/chrt.c | 34 ++++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) diff --git a/util-linux/chrt.c b/util-linux/chrt.c index 4dd78dabf..6e8f66741 100644 --- a/util-linux/chrt.c +++ b/util-linux/chrt.c @@ -39,6 +39,17 @@ # define SCHED_IDLE 5 #endif +//musl has no __MUSL__ or similar define to check for, +//but its has these lines: +// #define __NEED_fsblkcnt_t +// #define __NEED_fsfilcnt_t +#if defined(__linux__) && defined(__NEED_fsblkcnt_t) && defined(__NEED_fsfilcnt_t) +# define LIBC_IS_MUSL 1 +# include +#else +# define LIBC_IS_MUSL 0 +#endif + static const char *policy_name(int pol) { if (pol > 6) @@ -85,6 +96,7 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) char *priority = priority; /* for compiler */ const char *current_new; int policy = SCHED_RR; + int ret; opt = getopt32(argv, "^" "+" "mprfobi" @@ -132,7 +144,15 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) if (opt & OPT_p) { int pol; print_rt_info: +#if LIBC_IS_MUSL + /* musl libc returns ENOSYS for its sched_getscheduler library + * function, because the sched_getscheduler Linux kernel system call + * does not conform to Posix; so we use the system call directly + */ + pol = syscall(SYS_sched_getscheduler, pid); +#else pol = sched_getscheduler(pid); +#endif if (pol < 0) bb_perror_msg_and_die("can't %cet pid %u's policy", 'g', (int)pid); #ifdef SCHED_RESET_ON_FORK @@ -149,7 +169,12 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) printf("pid %u's %s scheduling policy: SCHED_%s\n", pid, current_new, policy_name(pol) ); - if (sched_getparam(pid, &sp)) +#if LIBC_IS_MUSL + ret = syscall(SYS_sched_getparam, pid, &sp); +#else + ret = sched_getparam(pid, &sp); +#endif + if (ret) bb_perror_msg_and_die("can't get pid %u's attributes", (int)pid); printf("pid %u's %s scheduling priority: %d\n", (int)pid, current_new, sp.sched_priority @@ -168,7 +193,12 @@ int chrt_main(int argc UNUSED_PARAM, char **argv) sched_get_priority_min(policy), sched_get_priority_max(policy) ); - if (sched_setscheduler(pid, policy, &sp) < 0) +#if LIBC_IS_MUSL + ret = syscall(SYS_sched_setscheduler, pid, policy, &sp); +#else + ret = sched_setscheduler(pid, policy, &sp); +#endif + if (ret) bb_perror_msg_and_die("can't %cet pid %u's policy", 's', (int)pid); if (!argv[0]) /* "-p PRIO PID [...]" */ -- cgit v1.2.3