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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: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20220822114648.791019324@infradead.org
This commit is contained in:
Peter Zijlstra 2022-08-22 13:18:18 +02:00
parent 5950e5d574
commit 1fbcaa923c
3 changed files with 14 additions and 13 deletions
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9
include/linux/umh.h
View File

@ -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;

10
init/do_mounts_initrd.c
View File

@ -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);

8
kernel/umh.c
View File

@ -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: