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SubjectRe: [PATCH] Make prepare_namespace() wait for devices
Andrew Morton wrote:
> On Thu, 31 May 2007 13:20:48 +0200 Pierre Ossman <drzeus-list@drzeus.cx> wrote:
>
>> What was the verdict here? Were you satisfied with this or do you need a change?
>>
>
>
> I was kinda hoing to see version #2 with that funny loop cleaned up a bit?
>
>

New patch with the layout you suggested. It may be fewer lines, but I
still say my version was more readable.

Rgds

--
-- Pierre Ossman

Linux kernel, MMC maintainer http://www.kernel.org
PulseAudio, core developer http://pulseaudio.org
rdesktop, core developer http://www.rdesktop.org

commit 6354cb955ce1602b7b259f525edac7c8f585574b
Author: Pierre Ossman <drzeus@drzeus.cx>
Date: Mon May 14 14:15:46 2007 +0200

init: wait for asynchronously scanned block devices

Some buses (e.g. USB and MMC) do their scanning of devices in the
background, causing a race between them and prepare_namespace().
In order to be able to use these buses without an initrd, we now
wait for the device specified in root= to actually show up.

If the device never shows up than we will hang in an infinite loop.
In order to not mess with setups that reboot on panic, the feature
must be turned on via the command line option "rootwait".

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

diff --git a/init/do_mounts.c b/init/do_mounts.c
index 46fe407..4e5ef6a 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -25,6 +25,7 @@ int __initdata rd_doload; /* 1 = load RAM disk, 0 = don't load */
int root_mountflags = MS_RDONLY | MS_SILENT;
char * __initdata root_device_name;
static char __initdata saved_root_name[64];
+int __initdata root_wait;

dev_t ROOT_DEV;

@@ -216,6 +217,14 @@ static int __init root_dev_setup(char *line)

__setup("root=", root_dev_setup);

+static int __init rootwait_setup(char *line)
+{
+ root_wait = simple_strtol(line,NULL,0);
+ return 1;
+}
+
+__setup("rootwait=", rootwait_setup);
+
static char * __initdata root_mount_data;
static int __init root_data_setup(char *str)
{
@@ -438,11 +447,20 @@ void __init prepare_namespace(void)
root_device_name += 5;
}

- is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
-
if (initrd_load())
goto out;

+ /* wait for any asynchronous scanning to complete */
+ if ((ROOT_DEV == 0) && root_wait) {
+ printk(KERN_INFO "Waiting for root device %s...\n",
+ saved_root_name);
+ while (driver_probe_done() != 0 ||
+ (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
+ msleep(100);
+ }
+
+ is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
+
if (is_floppy && rd_doload && rd_load_disk(0))
ROOT_DEV = Root_RAM0;
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