From 8d5f465a206e307bc47d8157b6c90152ddd2ab3c Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Tue, 29 Sep 2020 16:44:46 +0200 Subject: ash: jobs: Fix infinite loop in waitproc Upstream commit: Date: Fri, 10 Apr 2020 21:03:09 +1000 jobs: Fix infinite loop in waitproc After we changed the resetting of gotsigchld so that it is only done if jp is NULL, we can now get an infinite loop in waitproc if gotsigchld is set but there is no outstanding child because everything had been waited for previously without gotsigchld being zeroed. This patch fixes it by always zeroing gotsigchld as we did before. The bug that the previous patch was trying to fix is now resolved by switching the blocking mode to DOWAIT_NORMAL after the specified job has been completed so that we really do wait for all outstanding dead children. Reported-by: Harald van Dijk Fixes: 6c691b3e5099 ("jobs: Only clear gotsigchld when waiting...") Signed-off-by: Herbert Xu function old new delta dowait 553 631 +78 Signed-off-by: Denys Vlasenko --- shell/ash.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) (limited to 'shell/ash.c') diff --git a/shell/ash.c b/shell/ash.c index ac25866ec..13470b2fa 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -4453,15 +4453,28 @@ waitone(int block, struct job *job) static int dowait(int block, struct job *jp) { - int pid = block == DOWAIT_NONBLOCK ? got_sigchld : 1; + smallint gotchld = *(volatile smallint *)&got_sigchld; + int rpid; + int pid; + + if (jp && jp->state != JOBRUNNING) + block = DOWAIT_NONBLOCK; + + if (block == DOWAIT_NONBLOCK && !gotchld) + return 1; + + rpid = 1; - while (jp ? jp->state == JOBRUNNING : pid > 0) { - if (!jp) - got_sigchld = 0; + do { + got_sigchld = 0; pid = waitone(block, jp); - } + rpid &= !!pid; - return pid; + if (!pid || (jp && jp->state != JOBRUNNING)) + block = DOWAIT_NONBLOCK; + } while (pid >= 0); + + return rpid; } #if JOBS -- cgit v1.2.3