Marcelo, I originally submitted this patch against 2.4.18-rc2 and I
noticed that it has not been picked up yet. I've repatched it against
2.4.19-pre8 and retested it. This is to fix the problem where if you
run out of available pids, get_pid will cause a hang as it loops forever
through the tasks to try to find an available pid that doesn't exist.
Thanks,
Paul Larson
--- linux-2.4.19-pre8/kernel/fork.c Mon May 20 10:55:14 2002
+++ linux-getpid/kernel/fork.c Wed May 22 16:07:29 2002
@@ -21,6 +21,7 @@
#include <linux/completion.h>
#include <linux/namespace.h>
#include <linux/personality.h>
+#include <linux/compiler.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -86,12 +87,13 @@
{
static int next_safe = PID_MAX;
struct task_struct *p;
- int pid;
+ int pid, beginpid;
if (flags & CLONE_PID)
return current->pid;
spin_lock(&lastpid_lock);
+ beginpid = last_pid;
if((++last_pid) & 0xffff8000) {
last_pid = 300; /* Skip daemons etc. */
goto inside;
@@ -111,12 +113,16 @@
last_pid = 300;
next_safe = PID_MAX;
}
+ if(unlikely(last_pid == beginpid))
+ goto nomorepids;
goto repeat;
}
if(p->pid > last_pid && next_safe > p->pid)
next_safe = p->pid;
if(p->pgrp > last_pid && next_safe > p->pgrp)
next_safe = p->pgrp;
+ if(p->tgid > last_pid && next_safe > p->tgid)
+ next_safe = p->tgid;
if(p->session > last_pid && next_safe > p->session)
next_safe = p->session;
}
@@ -126,6 +132,11 @@
spin_unlock(&lastpid_lock);
return pid;
+
+nomorepids:
+ read_unlock(&tasklist_lock);
+ spin_unlock(&lastpid_lock);
+ return 0;
}
static inline int dup_mmap(struct mm_struct * mm)
@@ -624,6 +635,8 @@
copy_flags(clone_flags, p);
p->pid = get_pid(clone_flags);
+ if (p->pid == 0 && current->pid != 0)
+ goto bad_fork_cleanup;
p->run_list.next = NULL;
p->run_list.prev = NULL;
-
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This archive was generated by hypermail 2b29 : Thu May 23 2002 - 22:00:27 EST