Re: module tool with 2.6.9 limitation issue

[Randy.Dunlap]

yiding_wang@xxxxxxxxxxx wrote:
> I am using moudle-init-tools-3.1-pre6 with kernel 2.6.9. The new insmod seems have restrictions which failed using parameters to load a driver module.
>
> My module parameter is in the form of modname="*************** ****", a quite long one.
> Run - insmod modname.o modname="*********** *******" (with a script), it complains about the space and treats the string next to the space to be a "Unknown parameter".
>
> By replacing the space with any character, then it complains 
> "modname: string parameter too long"

Patch for that one is attached.  It might be overkill,
but it works with this patch (as long as parameter value length
is <= 1024 -- not that I tried one of that length).

Rusty or anyone else, where do the quotes come from?
Here's what I enter:
insmod test_module modprm="this test"

but the kernel sees this parameter string:
"modprm=this test"
(with the quotation marks).
Who/what moved the quotation marks?  Is bash doing any of that?
I don't see it in insmod or modprobe (with a quick look).

> Reducing the length of the parameter to less than 1k character works fine.

Right, parameter value length cannot be > 1024.

> Same long parameter string wit space in between works fine under 2.4.25 with original insmod.
>
> Questions:
> 1, Is this a bug or new insmod has restrictions? 

The limit is actually in linux/kernel/params.c, not in insmod.
It seems a little arbitrary, but a parameter that long also seems
quite excessive.  Just break it into multiple parameters.

> 2, If it is restriction on special character such as space, or limitation on parameter length, then why and what is the limit? 

Just 1024 bytes in total length.

> 3, If insmod has limitation, then what is better way to pass long parameter with some special character? 

Just break it into multiple parameters....

--
~Randy
linux-2610-rc1-bk21
description

Signed-off-by: Randy Dunlap <rddunlap@xxxxxxxx>

diffstat:=
 kernel/params.c |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)

diff -Naurp ./kernel/params.c~modprm_quoted ./kernel/params.c
--- ./kernel/params.c~modprm_quoted	2004-11-11 15:13:26.000000000 -0800
+++ ./kernel/params.c	2004-11-11 19:42:36.714124784 -0800
@@ -77,10 +77,16 @@ static int parse_one(char *param,
 static char *next_arg(char *args, char **param, char **val)
 {
 	unsigned int i, equals = 0;
-	int in_quote = 0;
+	int in_quote = 0, quoted = 0;
+	char *next;
 
 	/* Chew any extra spaces */
 	while (*args == ' ') args++;
+	if (*args == '"') {
+		args++;
+		in_quote = 1;
+		quoted = 1;
+	}
 
 	for (i = 0; args[i]; i++) {
 		if (args[i] == ' ' && !in_quote)
@@ -106,13 +112,16 @@ static char *next_arg(char *args, char *
 			if (args[i-1] == '"')
 				args[i-1] = '\0';
 		}
+		if (quoted && args[i-1] == '"')
+			args[i-1] = '\0';
 	}
 
 	if (args[i]) {
 		args[i] = '\0';
-		return args + i + 1;
+		next = args + i + 1;
 	} else
-		return args + i;
+		next = args + i;
+	return next;
 }
 
 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */