b612e5df45
Reset all signal handlers of the child not set to SIG_IGN to SIG_DFL. Mutually exclusive with CLONE_SIGHAND to not disturb other thread's signal handler. In the spirit of closer cooperation between glibc developers and kernel developers (cf. [2]) this patchset came out of a discussion on the glibc mailing list for improving posix_spawn() (cf. [1], [3], [4]). Kernel support for this feature has been explicitly requested by glibc and I see no reason not to help them with this. The child helper process on Linux posix_spawn must ensure that no signal handlers are enabled, so the signal disposition must be either SIG_DFL or SIG_IGN. However, it requires a sigprocmask to obtain the current signal mask and at least _NSIG sigaction calls to reset the signal handlers for each posix_spawn call or complex state tracking that might lead to data corruption in glibc. Adding this flags lets glibc avoid these problems. [1]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00149.html [3]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00158.html [4]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00160.html [2]: https://lwn.net/Articles/799331/ '[...] by asking for better cooperation with the C-library projects in general. They should be copied on patches containing ABI changes, for example. I noted that there are often times where C-library developers wish the kernel community had done things differently; how could those be avoided in the future? Members of the audience suggested that more glibc developers should perhaps join the linux-api list. The other suggestion was to "copy Florian on everything".' Cc: Florian Weimer <fweimer@redhat.com> Cc: libc-alpha@sourceware.org Cc: linux-api@vger.kernel.org Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20191014104538.3096-1-christian.brauner@ubuntu.com
116 lines
4.5 KiB
C
116 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_SCHED_H
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#define _UAPI_LINUX_SCHED_H
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#include <linux/types.h>
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/*
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* cloning flags:
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*/
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#define CSIGNAL 0x000000ff /* signal mask to be sent at exit */
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#define CLONE_VM 0x00000100 /* set if VM shared between processes */
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#define CLONE_FS 0x00000200 /* set if fs info shared between processes */
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#define CLONE_FILES 0x00000400 /* set if open files shared between processes */
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#define CLONE_SIGHAND 0x00000800 /* set if signal handlers and blocked signals shared */
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#define CLONE_PIDFD 0x00001000 /* set if a pidfd should be placed in parent */
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#define CLONE_PTRACE 0x00002000 /* set if we want to let tracing continue on the child too */
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#define CLONE_VFORK 0x00004000 /* set if the parent wants the child to wake it up on mm_release */
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#define CLONE_PARENT 0x00008000 /* set if we want to have the same parent as the cloner */
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#define CLONE_THREAD 0x00010000 /* Same thread group? */
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#define CLONE_NEWNS 0x00020000 /* New mount namespace group */
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#define CLONE_SYSVSEM 0x00040000 /* share system V SEM_UNDO semantics */
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#define CLONE_SETTLS 0x00080000 /* create a new TLS for the child */
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#define CLONE_PARENT_SETTID 0x00100000 /* set the TID in the parent */
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#define CLONE_CHILD_CLEARTID 0x00200000 /* clear the TID in the child */
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#define CLONE_DETACHED 0x00400000 /* Unused, ignored */
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#define CLONE_UNTRACED 0x00800000 /* set if the tracing process can't force CLONE_PTRACE on this clone */
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#define CLONE_CHILD_SETTID 0x01000000 /* set the TID in the child */
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#define CLONE_NEWCGROUP 0x02000000 /* New cgroup namespace */
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#define CLONE_NEWUTS 0x04000000 /* New utsname namespace */
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#define CLONE_NEWIPC 0x08000000 /* New ipc namespace */
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#define CLONE_NEWUSER 0x10000000 /* New user namespace */
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#define CLONE_NEWPID 0x20000000 /* New pid namespace */
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#define CLONE_NEWNET 0x40000000 /* New network namespace */
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#define CLONE_IO 0x80000000 /* Clone io context */
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/* Flags for the clone3() syscall. */
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#define CLONE_CLEAR_SIGHAND 0x100000000ULL /* Clear any signal handler and reset to SIG_DFL. */
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#ifndef __ASSEMBLY__
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/**
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* struct clone_args - arguments for the clone3 syscall
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* @flags: Flags for the new process as listed above.
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* All flags are valid except for CSIGNAL and
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* CLONE_DETACHED.
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* @pidfd: If CLONE_PIDFD is set, a pidfd will be
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* returned in this argument.
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* @child_tid: If CLONE_CHILD_SETTID is set, the TID of the
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* child process will be returned in the child's
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* memory.
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* @parent_tid: If CLONE_PARENT_SETTID is set, the TID of
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* the child process will be returned in the
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* parent's memory.
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* @exit_signal: The exit_signal the parent process will be
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* sent when the child exits.
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* @stack: Specify the location of the stack for the
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* child process.
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* @stack_size: The size of the stack for the child process.
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* @tls: If CLONE_SETTLS is set, the tls descriptor
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* is set to tls.
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*
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* The structure is versioned by size and thus extensible.
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* New struct members must go at the end of the struct and
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* must be properly 64bit aligned.
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*/
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struct clone_args {
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__aligned_u64 flags;
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__aligned_u64 pidfd;
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__aligned_u64 child_tid;
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__aligned_u64 parent_tid;
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__aligned_u64 exit_signal;
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__aligned_u64 stack;
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__aligned_u64 stack_size;
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__aligned_u64 tls;
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};
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#endif
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#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
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/*
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* Scheduling policies
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*/
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#define SCHED_NORMAL 0
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#define SCHED_FIFO 1
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#define SCHED_RR 2
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#define SCHED_BATCH 3
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/* SCHED_ISO: reserved but not implemented yet */
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#define SCHED_IDLE 5
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#define SCHED_DEADLINE 6
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/* Can be ORed in to make sure the process is reverted back to SCHED_NORMAL on fork */
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#define SCHED_RESET_ON_FORK 0x40000000
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/*
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* For the sched_{set,get}attr() calls
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*/
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#define SCHED_FLAG_RESET_ON_FORK 0x01
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#define SCHED_FLAG_RECLAIM 0x02
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#define SCHED_FLAG_DL_OVERRUN 0x04
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#define SCHED_FLAG_KEEP_POLICY 0x08
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#define SCHED_FLAG_KEEP_PARAMS 0x10
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#define SCHED_FLAG_UTIL_CLAMP_MIN 0x20
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#define SCHED_FLAG_UTIL_CLAMP_MAX 0x40
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#define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \
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SCHED_FLAG_KEEP_PARAMS)
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#define SCHED_FLAG_UTIL_CLAMP (SCHED_FLAG_UTIL_CLAMP_MIN | \
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SCHED_FLAG_UTIL_CLAMP_MAX)
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#define SCHED_FLAG_ALL (SCHED_FLAG_RESET_ON_FORK | \
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SCHED_FLAG_RECLAIM | \
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SCHED_FLAG_DL_OVERRUN | \
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SCHED_FLAG_KEEP_ALL | \
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SCHED_FLAG_UTIL_CLAMP)
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#endif /* _UAPI_LINUX_SCHED_H */
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