On Tue, Nov 20, 2018 at 1:05 AM Vlastimil Babka <vbabka@xxxxxxx> wrote: > > On 11/19/18 11:54 AM, Pavel Machek wrote: > > On Mon 2018-11-05 13:22:05, Daniel Colascione wrote: > >> State explicitly that holding a /proc/pid file descriptor open does > >> not reserve the PID. Also note that in the event of PID reuse, these > >> open file descriptors refer to the old, now-dead process, and not the > >> new one that happens to be named the same numeric PID. > >> > >> Signed-off-by: Daniel Colascione <dancol@xxxxxxxxxx> > >> --- > >> Documentation/filesystems/proc.txt | 7 +++++++ > >> 1 file changed, 7 insertions(+) > >> > >> Moved paragraphed to start of /proc/pid section; added signed-off-by. > >> > >> diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt > >> index 12a5e6e693b6..0b14460f721d 100644 > >> --- a/Documentation/filesystems/proc.txt > >> +++ b/Documentation/filesystems/proc.txt > >> @@ -125,6 +125,13 @@ process running on the system, which is named after the process ID (PID). > >> The link self points to the process reading the file system. Each process > >> subdirectory has the entries listed in Table 1-1. > >> > >> +Note that an open a file descriptor to /proc/<pid> or to any of its > >> +contained files or subdirectories does not prevent <pid> being reused > >> +for some other process in the event that <pid> exits. Operations on > > > > "does not" -> "may not"? > > > > We want to leave this unspecified, so that we can change it in future. > > Why can't the documentation describe the current implementation, and > change in the future if the implementation changes? I doubt somebody > would ever rely on the pid being reused while having the descriptor > open. How would that make sense? > Agreed. I am also of the opinion that this should be documented. - Joel
