init: multi param parsing regression since 3.4

["Benoît Thébaudeau" <benoit.thebaudeau@advansee.com>]

Hi Pawel, Rusty, all,

Since linux 3.4 (OK with 3.3.6), I get the following regression for UBI (built
in kernel):
[    1.327228] UBI: attaching mtd4 to ubi0
[    1.331082] UBI: physical eraseblock size:   131072 bytes (128 KiB)
[    1.337388] UBI: logical eraseblock size:    129024 bytes
[    1.342794] UBI: smallest flash I/O unit:    2048
[    1.347518] UBI: sub-page size:              512
[    1.352144] UBI: VID header offset:          512 (aligned 512)
[    1.357996] UBI: data offset:                2048
[    1.538686] UBI: max. sequence number:       456
[    1.551271] UBI: attached mtd4 to ubi0
[    1.555085] UBI: MTD device name:            "rootfs"
[    1.560147] UBI: MTD device size:            123 MiB
[    1.565133] UBI: number of good PEBs:        980
[    1.569757] UBI: number of bad PEBs:         4
[    1.574206] UBI: number of corrupted PEBs:   0
[    1.578669] UBI: max. allowed volumes:       128
[    1.583293] UBI: wear-leveling threshold:    4096
[    1.588015] UBI: number of internal volumes: 1
[    1.592465] UBI: number of user volumes:     1
[    1.596927] UBI: available PEBs:             0
[    1.601377] UBI: total number of reserved PEBs: 980
[    1.606273] UBI: number of PEBs reserved for bad PEB handling: 9
[    1.612288] UBI: max/mean erase counter: 3/1
[    1.616576] UBI: image sequence number:  1970526931
[    1.621483] UBI: background thread "ubi_bgt0d" started, PID 32
[    1.627362] UBI error: ubi_init: cannot attach mtd4

After some debugging, I found that this is caused by "ubi.mtd=rootfs" in my
kernel command line being parsed twice while appearing once in this line.

The root cause is "parse_args(initcall_level_names[level], ..." that you added
to init/main.c in commit #026cee0086fe1df4cf74691cf273062cc769617d, because
level 0 is shared by "Booting kernel" and "early parameters".

This may also cause issues for other modules.

Should "parse_args("Booting kernel", ..." have been removed with your commit?

OR

Should do_initcall_level() call parse_args() starting at level 1?

OR

Should the UBI module register to another level?

OR

It doesn't matter and it's up to the modules to be robust to multi param
parsing?

Regards,
Benoît (Please keep me Cc'ed)