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authorLinus Torvalds <torvalds@linux-foundation.org>2019-03-16 13:47:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-16 13:47:14 -0700
commita9dce6679d736cb3d612af39bab9f31f8db66f9b (patch)
tree7a5e010464d0154fce53aea3c9e3fac2b37c2912 /include
parentf67e3fb4891287b8248ebb3320f794b9f5e782d4 (diff)
parent575a0ae9744d571f7c6aae4487a05850baae9e1c (diff)
Merge tag 'pidfd-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull pidfd system call from Christian Brauner: "This introduces the ability to use file descriptors from /proc/<pid>/ as stable handles on struct pid. Even if a pid is recycled the handle will not change. For a start these fds can be used to send signals to the processes they refer to. With the ability to use /proc/<pid> fds as stable handles on struct pid we can fix a long-standing issue where after a process has exited its pid can be reused by another process. If a caller sends a signal to a reused pid it will end up signaling the wrong process. With this patchset we enable a variety of use cases. One obvious example is that we can now safely delegate an important part of process management - sending signals - to processes other than the parent of a given process by sending file descriptors around via scm rights and not fearing that the given process will have been recycled in the meantime. It also allows for easy testing whether a given process is still alive or not by sending signal 0 to a pidfd which is quite handy. There has been some interest in this feature e.g. from systems management (systemd, glibc) and container managers. I have requested and gotten comments from glibc to make sure that this syscall is suitable for their needs as well. In the future I expect it to take on most other pid-based signal syscalls. But such features are left for the future once they are needed. This has been sitting in linux-next for quite a while and has not caused any issues. It comes with selftests which verify basic functionality and also test that a recycled pid cannot be signaled via a pidfd. Jon has written about a prior version of this patchset. It should cover the basic functionality since not a lot has changed since then: https://lwn.net/Articles/773459/ The commit message for the syscall itself is extensively documenting the syscall, including it's functionality and extensibility" * tag 'pidfd-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: selftests: add tests for pidfd_send_signal() signal: add pidfd_send_signal() syscall
Diffstat (limited to 'include')
-rw-r--r--include/linux/proc_fs.h6
-rw-r--r--include/linux/syscalls.h3
-rw-r--r--include/uapi/asm-generic/unistd.h2
3 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index d0e1f1522a78..52a283ba0465 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -73,6 +73,7 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo
int (*show)(struct seq_file *, void *),
proc_write_t write,
void *data);
+extern struct pid *tgid_pidfd_to_pid(const struct file *file);
#else /* CONFIG_PROC_FS */
@@ -114,6 +115,11 @@ static inline int remove_proc_subtree(const char *name, struct proc_dir_entry *p
#define proc_create_net(name, mode, parent, state_size, ops) ({NULL;})
#define proc_create_net_single(name, mode, parent, show, data) ({NULL;})
+static inline struct pid *tgid_pidfd_to_pid(const struct file *file)
+{
+ return ERR_PTR(-EBADF);
+}
+
#endif /* CONFIG_PROC_FS */
struct net;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c2962953bf11..e446806a561f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -985,6 +985,9 @@ asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
unsigned mask, struct statx __user *buffer);
asmlinkage long sys_rseq(struct rseq __user *rseq, uint32_t rseq_len,
int flags, uint32_t sig);
+asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
+ siginfo_t __user *info,
+ unsigned int flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index bf4624efe5e6..dee7292e1df6 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -824,6 +824,8 @@ __SYSCALL(__NR_futex_time64, sys_futex)
__SYSCALL(__NR_sched_rr_get_interval_time64, sys_sched_rr_get_interval)
#endif
+#define __NR_pidfd_send_signal 424
+__SYSCALL(__NR_pidfd_send_signal, sys_pidfd_send_signal)
#define __NR_io_uring_setup 425
__SYSCALL(__NR_io_uring_setup, sys_io_uring_setup)
#define __NR_io_uring_enter 426