910831cb5c
Now that there are services other than PM and VFS that implement userland system calls directly, these services may need to know about events related to user processes. In particular, signal delivery may have to interrupt blocking system calls, and certain cleanup tasks may have to be performed after a user process exits. This patch aims to implement a generic, lasting solution for this problem, by allowing services to subscribe to "signal delivered" and/or "process exit" events from PM. PM publishes such events by sending messages to its subscribed services, which must then reply an acknowledgment message. For now, only the two aforementioned events are implemented, and only the IPC service makes use of the process event facility. The new process event publish/subscribe system replaces the previous VM notify-sig/watch-exit/query-exit system, which was unsound: 1) it allowed subscription to events from individual processes, and suffered from fundamental race conditions as a result; 2) it relied on "not too many" processes making use of the IPC server functionality in order to avoid loss of notifications. In addition, it had the "ipc" process name hardcoded, did not distinguish between signal delivery and exits, and added a roundtrip to VM for all events from all processes. Change-Id: I75ebad4bc54e646c6433f473294cb4003b2c3430
21 lines
496 B
C
21 lines
496 B
C
#include "syslib.h"
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#include <string.h>
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/*
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* Subscribe to a certain set of process events from PM. Subsequent calls will
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* replace the set, and the empty set (a zero mask) will unsubscribe the caller
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* altogether. Usage restrictions apply; see PM's event.c for details. Return
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* OK or a negative error code.
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*/
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int
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proceventmask(unsigned int mask)
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{
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message m;
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memset(&m, 0, sizeof(m));
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m.m_lsys_pm_proceventmask.mask = mask;
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return _taskcall(PM_PROC_NR, PM_PROCEVENTMASK, &m);
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}
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