Document the /proc/[pid]/task/[tid]/children interface from CRIU, and more importantly, document why it's usually not a good interface. --- man5/proc.5 | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/man5/proc.5 b/man5/proc.5 index 0970c72..ddb14cc 100644 --- a/man5/proc.5 +++ b/man5/proc.5 @@ -2325,14 +2325,33 @@ the corresponding files under .I task/[tid] may have different values (e.g., various fields in each of the .I task/[tid]/status -files may be different for each thread). - +files may be different for each thread), +.\" in particular: "children" :/ +or they might not exist in +.I /proc/[pid] +at all. .\" The following was still true as at kernel 2.6.13 In a multithreaded process, the contents of the .I /proc/[pid]/task directory are not available if the main thread has already terminated (typically by calling .BR pthread_exit (3)). + +.TP +.IR /proc/[pid]/task/[tid]/children " (since Linux 3.5)" +.\" commit 818411616baf46ceba0cff6f05af3a9b294734f7 +A space-separated list of child tasks of this task. +Each child task is represented by its TID. + +.\" see comments in get_children_pid() in fs/proc/array.c +This does not work properly if children of the target task exit while +the file is being read! +Exiting children may cause non-exiting children to be omitted from +the list. +This makes this interface even more unreliable than classic PID-based +approaches if the inspected task and its children aren't frozen, and +most code should probably not use this interface. + .TP .IR /proc/[pid]/timers " (since Linux 3.10)" .\" commit 5ed67f05f66c41e39880a6d61358438a25f9fee5 -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
