Commit 1fbcaa92 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

freezer,umh: Clean up freezer/initrd interaction 



handle_initrd() marks itself as PF_FREEZER_SKIP in order to ensure
that the UMH, which is going to freeze the system, doesn't
indefinitely wait for it's caller.

Rework things by adding UMH_FREEZABLE to indicate the completion is
freezable.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20220822114648.791019324@infradead.org
parent 5950e5d5

include/linux/umh.h

+5 −4
Original line number Diff line number Diff line
@@ -11,10 +11,11 @@ 
struct cred;

struct file;



#define UMH_NO_WAIT	0	/* don't wait at all */

#define UMH_WAIT_EXEC	1	/* wait for the exec, but not the process */

#define UMH_WAIT_PROC	2	/* wait for the process to complete */

#define UMH_KILLABLE	4	/* wait for EXEC/PROC killable */

#define UMH_NO_WAIT	0x00	/* don't wait at all */

#define UMH_WAIT_EXEC	0x01	/* wait for the exec, but not the process */

#define UMH_WAIT_PROC	0x02	/* wait for the process to complete */

#define UMH_KILLABLE	0x04	/* wait for EXEC/PROC killable */

#define UMH_FREEZABLE	0x08	/* wait for EXEC/PROC freezable */



struct subprocess_info {

	struct work_struct work;

init/do_mounts_initrd.c

+1 −9
Original line number Diff line number Diff line
@@ -99,19 +99,11 @@ static void __init handle_initrd(void) 
	init_mkdir("/old", 0700);

	init_chdir("/old");



	/*

	 * In case that a resume from disk is carried out by linuxrc or one of

	 * its children, we need to tell the freezer not to wait for us.

	 */

	current->flags |= PF_FREEZER_SKIP;



	info = call_usermodehelper_setup("/linuxrc", argv, envp_init,

					 GFP_KERNEL, init_linuxrc, NULL, NULL);

	if (!info)

		return;

	call_usermodehelper_exec(info, UMH_WAIT_PROC);



	current->flags &= ~PF_FREEZER_SKIP;

	call_usermodehelper_exec(info, UMH_WAIT_PROC|UMH_FREEZABLE);



	/* move initrd to rootfs' /old */

	init_mount("..", ".", NULL, MS_MOVE, NULL);

kernel/umh.c

+8 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/async.h>

#include <linux/uaccess.h>

#include <linux/initrd.h>

#include <linux/freezer.h>



#include <trace/events/module.h>
@@ -436,6 +437,9 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) 
	if (wait == UMH_NO_WAIT)	/* task has freed sub_info */

		goto unlock;



	if (wait & UMH_FREEZABLE)

		freezer_do_not_count();



	if (wait & UMH_KILLABLE) {

		retval = wait_for_completion_killable(&done);

		if (!retval)
@@ -448,6 +452,10 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) 
	}



	wait_for_completion(&done);



	if (wait & UMH_FREEZABLE)

		freezer_count();



wait_done:

	retval = sub_info->retval;

out: