The patch makes __do_SAK() iterate a next thread files only in case of the thread's files are different to previous. I.e., if all threads points the same files_struct, the files will be iterated only once.
Since all threads have the same files_struct is the generic case for most Linux systems, this improvement should clearly speed up __do_SAK() execution. Also, for_each_process()/for_each_thread() are used instead of do_each_thread()/while_each_thread(). This prepares __do_SAK() to become tasklist_lock free, and will be made in next patch. https://jira.sw.ru/browse/PSBM-80340 Suggested-by: Oleg Nesterov <o...@redhat.com> Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com> Reviewed-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com> Rebase to vz8: - Change send_sig to group_send_sig_info to respect ms commit a8ebd17160ce ("tty_io: Use group_send_sig_info in __do_SACK to note it is a session being killed") (cherry picked from vz7 commit d61ca741c3ae ("tty: Avoid threads files iterations in __do_SAK()")) Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com> Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com> --- drivers/tty/tty_io.c | 37 +++++++++++++++++++++++++------------ 1 file changed, 25 insertions(+), 12 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index a6230b25fbe5..535f40164c2b 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3031,7 +3031,8 @@ void __do_SAK(struct tty_struct *tty) #ifdef TTY_SOFT_SAK tty_hangup(tty); #else - struct task_struct *g, *p; + struct task_struct *p, *t; + struct files_struct *files; struct pid *session; int i; unsigned long flags; @@ -3056,22 +3057,34 @@ void __do_SAK(struct tty_struct *tty) } while_each_pid_task(session, PIDTYPE_SID, p); /* Now kill any processes that happen to have the tty open */ - do_each_thread(g, p) { + for_each_process(p) { if (p->signal->tty == tty) { tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n", task_pid_nr(p), p->comm); - group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID); - continue; + goto kill; } - task_lock(p); - i = iterate_fd(p->files, 0, this_tty, tty); - if (i != 0) { - tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n", - task_pid_nr(p), p->comm, i - 1); - group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID); + + files = NULL; + for_each_thread(p, t) { + if (t->files == files) /* racy but we do not care */ + continue; + + task_lock(t); + files = t->files; + i = iterate_fd(files, 0, this_tty, tty); + task_unlock(t); + + if (i != 0) { + dev_notice(tty->dev, "SAK: killed process %d (%s): by fd#%d\n", + task_pid_nr(p), p->comm, i - 1); + goto kill; + } } - task_unlock(p); - } while_each_thread(g, p); + + continue; +kill: + group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID); + } read_unlock(&tasklist_lock); put_pid(session); #endif _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
