linux-kernel - Re: [patch 1/7] Extended crashkernel command line

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Message-ID: <20070926161602.GA26909@suse.de>
Date:	Wed, 26 Sep 2007 18:16:02 +0200
From:	Bernhard Walle <bwalle@...e.de>
To:	Oleg Verych <olecom@...wer.upol.cz>
Cc:	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
	kexec@...ts.infradead.org, akpm@...ux-foundation.org
Subject: Re: [patch 1/7] Extended crashkernel command line

* Oleg Verych <olecom@...wer.upol.cz> [2007-09-25 22:53]:
> 
> > + *
> > + * The function returns 0 on success and -EINVAL on failure.
> > + */
> > +static int __init parse_crashkernel_mem(char 			*cmdline,
> > +					unsigned long long	system_ram,
> > +					unsigned long long	*crash_size,
> > +					unsigned long long	*crash_base)
> > +{
> > +	char *cur = cmdline;
> > +
> > +	/* for each entry of the comma-separated list */
> > +	do {
> > +		unsigned long long start = 0, end = ULLONG_MAX;
> > +		unsigned long long size = -1;
> 
> memparse(), as a wrapper for somple_strtoll(), always have a return value
> (zero by default).
> <http://article.gmane.org/gmane.linux.kernel/583426>

Ok, that's fixed now, see patch below.

> And why not to make overall result reliable? This is kernel after all.
> 
> I.e. if there's valid `crashkernel=' option, but some parsing errors, why
> not to apply some heuristics with warning in syslog, if user have some
> conf, bootloader (random) errors, but feature still works?

I'm against guessing. The user has to specify a parameter which is
right according to syntax.

However, I plan to make a patch that the kernel can detect a sensible
offset automatically for i386 and x86_64 as it's done in ia64. Since
both architectures have a relocatable kernel now, that makes perfectly
sense. But that's another patch.

---

This patches improves error handling in parse_crashkernel_mem() by comparing
the return pointer of memparse() with the input pointer and also replaces
all printk(KERN_WARNING msg) with pr_warning(msg).


Signed-off-by: Bernhard Walle <bwalle@...e.de>

---
 kernel/kexec.c |   31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1172,33 +1172,50 @@ static int __init parse_crashkernel_mem(
 	do {
 		unsigned long long start = 0, end = ULLONG_MAX;
 		unsigned long long size = -1;
+		char *tmp;
 
 		/* get the start of the range */
-		start = memparse(cur, &cur);
+		start = memparse(cur, &tmp);
+		if (cur == tmp) {
+			pr_warning("crashkernel: Memory value expected\n");
+			return -EINVAL;
+		}
+		cur = tmp;
 		if (*cur != '-') {
-			printk(KERN_WARNING "crashkernel: '-' expected\n");
+			pr_warning("crashkernel: '-' expected\n");
 			return -EINVAL;
 		}
 		cur++;
 
 		/* if no ':' is here, than we read the end */
 		if (*cur != ':') {
-			end = memparse(cur, &cur);
+			end = memparse(cur, &tmp);
+			if (cur == tmp) {
+				pr_warning("crashkernel: Memory "
+						"value expected\n");
+				return -EINVAL;
+			}
+			cur = tmp;
 			if (end <= start) {
-				printk(KERN_WARNING "crashkernel: end <= start\n");
+				pr_warning("crashkernel: end <= start\n");
 				return -EINVAL;
 			}
 		}
 
 		if (*cur != ':') {
-			printk(KERN_WARNING "crashkernel: ':' expected\n");
+			pr_warning("crashkernel: ':' expected\n");
 			return -EINVAL;
 		}
 		cur++;
 
-		size = memparse(cur, &cur);
+		size = memparse(cur, &tmp);
+		if (cur == tmp) {
+			pr_warning("Memory value expected\n");
+			return -EINVAL;
+		}
+		cur = tmp;
 		if (size < 0) {
-			printk(KERN_WARNING "crashkernel: invalid size\n");
+			pr_warning("crashkernel: invalid size\n");
 			return -EINVAL;
 		}
 
-
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