netdev - Re: [PATCH RFC 0/4] ARM/KGDB: Some fixes for SMP machines

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 7 Jul 2010 21:54:06 +0400
From:	Anton Vorontsov <cbouatmailru@...il.com>
To:	kgdb-bugreport@...ts.sourceforge.net
Cc:	Russell King <linux@....linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Jason Wessel <jason.wessel@...driver.com>,
	netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RFC 0/4] ARM/KGDB: Some fixes for SMP machines

On Wed, Jul 07, 2010 at 09:12:22PM +0400, Anton Vorontsov wrote:
[...] 
> 2. The patches are against a heavily patched kernel, and so far
>    I didn't rebase them onto the 'debug core' rework as found
>    in the very latest mainline kernels. I'll rebase the patches
>    soon, so for now this is just an RFC.

BTW, I'm testing with another small fixup applied, I didn't send
it as a patch because this deadlock was already fixed in the
debug_core implementation (which KGDB is using nowadays). But
for the completeness, here it is:

(Don't deadlock if there's a wannabe-master CPUs, which entered
KGDB via exception, not NMI/IPI).

diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index e7a2274..65bf75d 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -1522,7 +1522,9 @@ return_normal:
 		 * from the debugger.
 		 */
 		for_each_online_cpu(i) {
-			while (atomic_read(&cpu_in_kgdb[i]))
+			while (atomic_read(&cpu_in_kgdb[i]) &&
+					!(kgdb_info[i].exception_state &
+						DCPU_WANT_MASTER))
 				cpu_relax();
 		}
 	}
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html