Hi, Greg: > Shouldn't there also be a manpage update, and a kselftest added for this > new user/kernel api that is being created? > I will submit a patch for manpage update once the code is accepted. Regarding the kselftest, I am not sure. Once the prctl() is limited to self (which I will do), the logic would be pretty straightforward. Not sure if the selftest would add much value. Thanks. -- Enke On 10/12/18 11:40 PM, Greg Kroah-Hartman wrote: > On Fri, Oct 12, 2018 at 05:33:35PM -0700, Enke Chen wrote: >> For simplicity and consistency, this patch provides an implementation >> for signal-based fault notification prior to the coredump of a child >> process. A new prctl command, PR_SET_PREDUMP_SIG, is defined that can >> be used by an application to express its interest and to specify the >> signal (SIGCHLD or SIGUSR1 or SIGUSR2) for such a notification. A new >> signal code (si_code), CLD_PREDUMP, is also defined for SIGCHLD. >> >> Background: >> >> As the coredump of a process may take time, in certain time-sensitive >> applications it is necessary for a parent process (e.g., a process >> manager) to be notified of a child's imminent death before the coredump >> so that the parent process can act sooner, such as re-spawning an >> application process, or initiating a control-plane fail-over. >> >> Currently there are two ways for a parent process to be notified of a >> child process's state change. One is to use the POSIX signal, and >> another is to use the kernel connector module. The specific events and >> actions are summarized as follows: >> >> Process Event POSIX Signal Connector-based >> ---------------------------------------------------------------------- >> ptrace_attach() do_notify_parent_cldstop() proc_ptrace_connector() >> SIGCHLD / CLD_STOPPED >> >> ptrace_detach() do_notify_parent_cldstop() proc_ptrace_connector() >> SIGCHLD / CLD_CONTINUED >> >> pre_coredump/ N/A proc_coredump_connector() >> get_signal() >> >> post_coredump/ do_notify_parent() proc_exit_connector() >> do_exit() SIGCHLD / exit_signal >> ---------------------------------------------------------------------- >> >> As shown in the table, the signal-based pre-coredump notification is not >> currently available. In some cases using a connector-based notification >> can be quite complicated (e.g., when a process manager is written in shell >> scripts and thus is subject to certain inherent limitations), and a >> signal-based notification would be simpler and better suited. >> >> Signed-off-by: Enke Chen <enkechen@xxxxxxxxx> >> --- >> arch/x86/kernel/signal_compat.c | 2 +- >> include/linux/sched.h | 4 ++ >> include/linux/signal.h | 5 +++ >> include/uapi/asm-generic/siginfo.h | 3 +- >> include/uapi/linux/prctl.h | 4 ++ >> kernel/fork.c | 1 + >> kernel/signal.c | 51 +++++++++++++++++++++++++ >> kernel/sys.c | 77 ++++++++++++++++++++++++++++++++++++++ >> 8 files changed, 145 insertions(+), 2 deletions(-) > > Shouldn't there also be a manpage update, and a kselftest added for this > new user/kernel api that is being created? > > thanks, > > greg k-h >
