Messages in this thread | | | Date | Sat, 25 Aug 2012 12:31:49 +0300 | From | Shmulik Ladkani <> | Subject | Re: [PATCH v2] mtd: cmdlinepart: fix the wrong check condition |
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Hi Huang, Artem,
On Sat, 25 Aug 2012 16:06:50 -0400 Huang Shijie <shijie8@gmail.com> wrote: > diff --git a/drivers/mtd/cmdlinepart.c b/drivers/mtd/cmdlinepart.c > index fc960a3..216d751 100644 > --- a/drivers/mtd/cmdlinepart.c > +++ b/drivers/mtd/cmdlinepart.c > @@ -322,13 +322,16 @@ static int parse_cmdline_partitions(struct mtd_info *master, > struct cmdline_mtd_partition *part; > const char *mtd_id = master->name; > > + if (!mtd_id) > + return 0; > + > /* parse command line */ > if (!cmdline_parsed) > mtdpart_setup_real(cmdline); > > for(part = partitions; part; part = part->next) > { > - if ((!mtd_id) || (!strcmp(part->mtd_id, mtd_id))) > + if (!strcmp(part->mtd_id, mtd_id)) > { > for(i = 0, offset = 0; i < part->num_parts; i++) > {
This changes the behavior of cmdling parsing, which might affect users expecting the old behavior.
According to the remark above 'parse_cmdline_partitions':
* It returns partitions for the requested mtd device, or * the first one in the chain if a NULL mtd_id is passed in.
I think the purpose of a NULL 'mtd_id' was to support simple systems where there's a single driver and a single chip. The driver could be dumb, not specifying its 'mtd_info->name' (thus, a NULL mtd_id is passed).
In this case, since the system is simply configured (one driver, one chip), 'parse_cmdline_partitions' simply disregards the "mtd-id" name specified in the cmdline string, allowing the user to present some arbitrary string there.
I quite remember seeing this pattern somewhere in the past, I don't know if it's still used, though.
Obviously if you have many drivers (and many chips) in a system, that won't work; the drivers must initialize 'mtd_info->name' and the user should present a cmdline that has explicit 'mtd-id's.
So question is, would we like to prohibit NULL mtd-id?
If so, we must make sure all drivers are properly assigning their 'mtd_info->name', and all users correctly specifying 'mtd-id' in their "mtdparts" cmdline strings.
Regards, Shmulik
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