On Fri, Jun 19, 2020 at 09:17:00PM +0000, Luis Chamberlain wrote:

On Thu, Jun 18, 2020 at 04:46:27PM +0200, Christoph Hellwig wrote:

quoted

--- a/kernel/exit.c
+++ b/kernel/exit.c

@@ -1626,6 +1626,22 @@ long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
 	return ret;
 }
 
+int kernel_wait(pid_t pid, int *stat)
+{
+	struct wait_opts wo = {
+		.wo_type	= PIDTYPE_PID,
+		.wo_pid		= find_get_pid(pid),
+		.wo_flags	= WEXITED,
+	};
+	int ret;
+
+	ret = do_wait(&wo);
+	if (ret > 0 && wo.wo_stat)
+		*stat = wo.wo_stat;

Since all we care about is WEXITED, that could be simplified
to something like this:

if (ret > 0 && KWIFEXITED(wo.wo_stat)
 	*stat = KWEXITSTATUS(wo.wo_stat)

Otherwise callers have to use W*() wrappers.

quoted

+	put_pid(wo.wo_pid);
+	return ret;
+}

Then we don't get *any* in-kernel code dealing with the W*() crap.
I just unwrapped this for the umh [0], given that otherwise we'd
have to use KW*() callers elsewhere. Doing it upshot one level
further would be even better.

[0] https://lkml.kernel.org/r/20200610154923.27510-1-mcgrof@kernel.org              

Do you just want to pick this patch up, add your suggested bits and
add it to the beginning of your series?  That should clean the whole
thing up a bit.  Nothing else in this series depends on the patch.

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