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/freebsd/bin/pwait/
H A Dpwait.1diff 5bdce6ff546e00673f9f515d2165d02901e858aa Thu Jan 21 22:26:15 CET 2021 Alexander V. Chernikov <melifaro@FreeBSD.org> Remove deadlock in rc caused by pwait waiting for itself.

The following situation can trigger the deadlock:
1) Long time ago a_service was started through rc.d
2) We want to restart a_service and issue service a_service restart
3) rc.subr reads current process PID (via file or process),
sends TERM signal and runs pwait with PID harvested
4) a_service process dies very quickly so it's PID becomes available.
It is possible that while original process was running,
PID counter overflowed and pwait got assigned a_service's PID.

This patch ignores pid(s) to wait that are equal to pwait PID.

Reported by: Dan McGregor, Boris Lytochkin
Submitted by: Boris Lytochkin <lytboris at gmail.com>
Reviewed By: 0mp
MFC after: 2 weeks
PR: 218598
Differential Revision: https://reviews.freebsd.org/D28240
H A Dpwait.cdiff 5bdce6ff546e00673f9f515d2165d02901e858aa Thu Jan 21 22:26:15 CET 2021 Alexander V. Chernikov <melifaro@FreeBSD.org> Remove deadlock in rc caused by pwait waiting for itself.

The following situation can trigger the deadlock:
1) Long time ago a_service was started through rc.d
2) We want to restart a_service and issue service a_service restart
3) rc.subr reads current process PID (via file or process),
sends TERM signal and runs pwait with PID harvested
4) a_service process dies very quickly so it's PID becomes available.
It is possible that while original process was running,
PID counter overflowed and pwait got assigned a_service's PID.

This patch ignores pid(s) to wait that are equal to pwait PID.

Reported by: Dan McGregor, Boris Lytochkin
Submitted by: Boris Lytochkin <lytboris at gmail.com>
Reviewed By: 0mp
MFC after: 2 weeks
PR: 218598
Differential Revision: https://reviews.freebsd.org/D28240