[PATCH] swsusp: debugging

Add a swsusp debugging mode.  This does everything that's needed for a suspend
except for actually suspending.  So we can look in the log messages and work
out a) what code is being slow and b) which drivers are misbehaving.

(1)
# echo testproc > /sys/power/disk
# echo disk > /sys/power/state

This should turn off the non-boot CPU, freeze all processes, wait for 5
seconds and then thaw the processes and the CPU.

(2)
# echo test > /sys/power/disk
# echo disk > /sys/power/state

This should turn off the non-boot CPU, freeze all processes, shrink
memory, suspend all devices, wait for 5 seconds, resume the devices etc.

Cc: Pavel Machek <pavel@ucw.cz>
Cc: Stefan Seyfried <seife@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 28 insertions, 9 deletions

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index d3a158a60312..b1fb7866b0b3 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -71,7 +71,7 @@ static inline void platform_finish(void)
 
 static int prepare_processes(void)
 {
-        int error;
+        int error = 0;
 
         pm_prepare_console();
 
@@ -84,6 +84,12 @@ static int prepare_processes(void)
                 goto thaw;
         }
 
+        if (pm_disk_mode == PM_DISK_TESTPROC) {
+                printk("swsusp debug: Waiting for 5 seconds.\n");
+                mdelay(5000);
+                goto thaw;
+        }
+
         /* Free memory before shutting down devices. */
         if (!(error = swsusp_shrink_memory()))
                 return 0;
@@ -120,13 +126,21 @@ int pm_suspend_disk(void)
         if (error)
                 return error;
 
+        if (pm_disk_mode == PM_DISK_TESTPROC)
+                goto Thaw;
+
         suspend_console();
         error = device_suspend(PMSG_FREEZE);
         if (error) {
                 resume_console();
                 printk("Some devices failed to suspend\n");
-                unprepare_processes();
-                return error;
+                goto Thaw;
+        }
+
+        if (pm_disk_mode == PM_DISK_TEST) {
+                printk("swsusp debug: Waiting for 5 seconds.\n");
+                mdelay(5000);
+                goto Done;
         }
 
         pr_debug("PM: snapshotting memory.\n");
@@ -143,16 +157,17 @@ int pm_suspend_disk(void)
                         power_down(pm_disk_mode);
                 else {
                         swsusp_free();
-                        unprepare_processes();
-                        return error;
+                        goto Thaw;
                 }
-        } else
+        } else {
                 pr_debug("PM: Image restored successfully.\n");
+        }
 
         swsusp_free();
  Done:
         device_resume();
         resume_console();
+ Thaw:
         unprepare_processes();
         return error;
 }
@@ -249,6 +264,8 @@ static const char * const pm_disk_modes[] = {
         [PM_DISK_PLATFORM]      = "platform",
         [PM_DISK_SHUTDOWN]      = "shutdown",
         [PM_DISK_REBOOT]        = "reboot",
+        [PM_DISK_TEST]          = "test",
+        [PM_DISK_TESTPROC]      = "testproc",
 };
 
 /**
@@ -303,17 +320,19 @@ static ssize_t disk_store(struct subsystem * s, const char * buf, size_t n)
                 }
         }
         if (mode) {
-                if (mode == PM_DISK_SHUTDOWN || mode == PM_DISK_REBOOT)
+                if (mode == PM_DISK_SHUTDOWN || mode == PM_DISK_REBOOT ||
+                     mode == PM_DISK_TEST || mode == PM_DISK_TESTPROC) {
                         pm_disk_mode = mode;
-                else {
+                } else {
                         if (pm_ops && pm_ops->enter &&
                             (mode == pm_ops->pm_disk_mode))
                                 pm_disk_mode = mode;
                         else
                                 error = -EINVAL;
                 }
-        } else
+        } else {
                 error = -EINVAL;
+        }
 
         pr_debug("PM: suspend-to-disk mode set to '%s'\n",
                  pm_disk_modes[mode]);