Hi Cai,
Thanks very much for explaining everything.
Regards--
Subrata
On Tue, 2008-08-12 at 16:48 +0800, Cai Qian wrote:
Hi Subrata,
From: Subrata Modak [EMAIL PROTECTED]
Subject: Re: [LTP] [RFC] [KDUMP] [PROPOSED WORK] kdump on Xen hypervisor and
guests, more tests for utilities, like
Fix compiling warning on xchg(kexec_lock, 0) in kernel_kexec().
Signed-off-by: Huang Ying [EMAIL PROTECTED]
---
kernel/kexec.c |4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1433,6 +1433,7 @@ module_init(crash_save_vmcoreinfo_init)
On Wed, 13 Aug 2008 17:12:40 +0800 Huang Ying [EMAIL PROTECTED] wrote:
Fix compiling warning on xchg(kexec_lock, 0) in kernel_kexec().
Would prefer that thi code not use such a peculair idiom. I don't
believe that it needs to.
I guess that's a separate activity.
---
kernel/kexec.c |
On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
reminding.
Signed-off-by: Huang Ying [EMAIL PROTECTED]
---
include/asm-x86/kexec.h |3 +++
1 file changed, 3 insertions(+)
---
On Wed, 13 Aug 2008, Huang Ying wrote:
- xchg(kexec_lock, 0);
+ locked = xchg(kexec_lock, 0);
+ BUG_ON(!locked);
Why do you want to do this at all?
And why do you implement your locks with xchg() in the first place? That's
total and utter crap.
Hint: we have _real_ locking
On Wed, 13 Aug 2008, Andrew Morton wrote:
We don't need to create that local. I queued this:
No, please don't.
Just don't take this whole patch-series until it's cleaned up. There is
absolutely no excuse for using xchg as a locking primitive. Nothing like
this should be queued anywhere,
On Wed, 13 Aug 2008 09:19:27 -0400 Vivek Goyal [EMAIL PROTECTED] wrote:
On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
reminding.
Signed-off-by: Huang Ying [EMAIL PROTECTED]
---
* Andrew Morton [EMAIL PROTECTED] wrote:
instead? Not that that's really right either, but at least it avoids
the _ridiculous_ crap. The real solution is probably to use a
spinlock and trylock/unlock.
Or test_and_set_bit(). That's what I've been saying too, only
differently ;)
On Wed, Aug 13, 2008 at 11:12:48AM -0700, Eric W. Biederman wrote:
Linus Torvalds [EMAIL PROTECTED] writes:
On Wed, 13 Aug 2008, Huang Ying wrote:
- xchg(kexec_lock, 0);
+ locked = xchg(kexec_lock, 0);
+ BUG_ON(!locked);
Why do you want to do this at all?
And why do you
On Wed, 13 Aug 2008 11:12:48 -0700
[EMAIL PROTECTED] (Eric W. Biederman) wrote:
Linus Torvalds [EMAIL PROTECTED] writes:
On Wed, 13 Aug 2008, Huang Ying wrote:
- xchg(kexec_lock, 0);
+ locked = xchg(kexec_lock, 0);
+ BUG_ON(!locked);
Why do you want to do this at all?
And
On Wed, 13 Aug 2008, Andrew Morton wrote:
- * in interrupt context :)
+ * Return true if we acquired the lock
*/
-static int kexec_lock;
+static inline bool kexec_trylock(void)
+{
+ return !test_and_set_bit(0, kexec_bitlock);
Nope. That needs to be an unsigned long.
But more
On Wed, 13 Aug 2008 12:50:57 -0700 (PDT)
Linus Torvalds [EMAIL PROTECTED] wrote:
On Wed, 13 Aug 2008, Andrew Morton wrote:
- * in interrupt context :)
+ * Return true if we acquired the lock
*/
-static int kexec_lock;
+static inline bool kexec_trylock(void)
+{
+ return
On Wed, 2008-08-13 at 12:44 -0700, Andrew Morton wrote:
- Is xchg() guaranteed to be atomic? That's what atomic_xchg() is for.
Yes, xchg() is guaranteed to be atomic. atomic_xchg() applies only to
the atomic_t type, and is almost always #defined to xchg().
- xchg() isn't guaranteed to exist
On Wed, 13 Aug 2008 13:13:13 -0700 (PDT)
Linus Torvalds [EMAIL PROTECTED] wrote:
Used a bitop to preserve the runtime checking in there. spin_unlock()
doesn't return the previous lockedness.
Umm. spin_unlock does a lot more when you have lock debugging on, and
doesn't do useless crap
On Wed, 13 Aug 2008, Andrew Morton wrote:
#2:
I thought you said there were things that want to sleep in the region?
If so, spinlocks will work as long as you don't have CONFIG_PREEMPT or
lock validation (there's no way to deadlock thanks to all the lock getters
using the trylock
On Wed, 13 Aug 2008 13:31:24 -0700 (PDT)
Linus Torvalds [EMAIL PROTECTED] wrote:
On Wed, 13 Aug 2008, Andrew Morton wrote:
#2:
I thought you said there were things that want to sleep in the region?
be reasonable - that was over five minutes ago.
---
On Wed, Aug 13, 2008 at 01:41:18PM -0700, Andrew Morton wrote:
On Wed, 13 Aug 2008 13:31:24 -0700 (PDT)
Linus Torvalds [EMAIL PROTECTED] wrote:
On Wed, 13 Aug 2008, Andrew Morton wrote:
#2:
I thought you said there were things that want to sleep in the region?
be reasonable -
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