* [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
@ 2011-11-23 10:11 Michael Holzheu
2011-11-23 10:22 ` Simon Horman
0 siblings, 1 reply; 8+ messages in thread
From: Michael Holzheu @ 2011-11-23 10:11 UTC (permalink / raw)
To: akpm
Cc: Eric W. Biederman, Vivek Goyal, schwidefsky, heiko.carstens,
kexec, linux-kernel
From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Currently it is possible to set the crash_size via the sysfs
/sys/kernel/kexec_crash_size even if no crash kernel memory has
been defined with the "crashkernel" parameter. In this case
"crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
Unfortunately resource_size(&crashk_res) returns 1 in this case.
This breaks the s390 implementation of crash_(un)map_reserved_pages().
To fix the problem the correct "old_size" is now calculated in
crash_shrink_memory(). "old_size is set to "0" if crashk_res is
not initialized. With this change crash_shrink_memory() will do nothing,
when "crashk_res" is not initialized. It will return "0" for
"echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
"echo [not zero] > /sys/kernel/kexec_crash_size".
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
---
kernel/kexec.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran
int crash_shrink_memory(unsigned long new_size)
{
int ret = 0;
- unsigned long start, end;
+ unsigned long start, end, old_size;
mutex_lock(&kexec_mutex);
@@ -1141,10 +1141,10 @@ int crash_shrink_memory(unsigned long ne
}
start = crashk_res.start;
end = crashk_res.end;
-
- if (new_size >= end - start + 1) {
+ old_size = (end == 0) ? 0 : end - start + 1;
+ if (new_size >= old_size) {
ret = -EINVAL;
- if (new_size == end - start + 1)
+ if (new_size == old_size)
ret = 0;
goto unlock;
}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
2011-11-23 10:11 [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size Michael Holzheu
@ 2011-11-23 10:22 ` Simon Horman
2011-11-23 13:18 ` [PATCH v2] " Michael Holzheu
0 siblings, 1 reply; 8+ messages in thread
From: Simon Horman @ 2011-11-23 10:22 UTC (permalink / raw)
To: Michael Holzheu
Cc: akpm, heiko.carstens, kexec, linux-kernel, Eric W. Biederman,
schwidefsky, Vivek Goyal
On Wed, Nov 23, 2011 at 11:11:08AM +0100, Michael Holzheu wrote:
> From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
>
> Currently it is possible to set the crash_size via the sysfs
> /sys/kernel/kexec_crash_size even if no crash kernel memory has
> been defined with the "crashkernel" parameter. In this case
> "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
> Unfortunately resource_size(&crashk_res) returns 1 in this case.
> This breaks the s390 implementation of crash_(un)map_reserved_pages().
>
> To fix the problem the correct "old_size" is now calculated in
> crash_shrink_memory(). "old_size is set to "0" if crashk_res is
> not initialized. With this change crash_shrink_memory() will do nothing,
> when "crashk_res" is not initialized. It will return "0" for
> "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
> "echo [not zero] > /sys/kernel/kexec_crash_size".
>
> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
> ---
> kernel/kexec.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran
> int crash_shrink_memory(unsigned long new_size)
> {
> int ret = 0;
> - unsigned long start, end;
> + unsigned long start, end, old_size;
>
> mutex_lock(&kexec_mutex);
>
> @@ -1141,10 +1141,10 @@ int crash_shrink_memory(unsigned long ne
> }
> start = crashk_res.start;
> end = crashk_res.end;
> -
> - if (new_size >= end - start + 1) {
> + old_size = (end == 0) ? 0 : end - start + 1;
> + if (new_size >= old_size) {
> ret = -EINVAL;
> - if (new_size == end - start + 1)
> + if (new_size == old_size)
> ret = 0;
I wonder if while we are here we could clean up the logic above a little.
To my mind both
ret = new_size == old_size ? 0 : -EINVAL;
and
if (new_size == old_size)
ret = 0;
else
ret = -EINVAL;
are easier on the eyes than the current logic.
> goto unlock;
> }
But I am happy with the patch without my above suggestion.
Reviewed-by-by: Simon Horman <horms@verge.net.au>
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
2011-11-23 10:22 ` Simon Horman
@ 2011-11-23 13:18 ` Michael Holzheu
2011-11-23 13:34 ` Dave Young
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Michael Holzheu @ 2011-11-23 13:18 UTC (permalink / raw)
To: akpm
Cc: Simon Horman, heiko.carstens, kexec, linux-kernel,
Eric W. Biederman, schwidefsky, akpm, Vivek Goyal
From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Currently it is possible to set the crash_size via the sysfs
/sys/kernel/kexec_crash_size even if no crash kernel memory has
been defined with the "crashkernel" parameter. In this case
"crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
Unfortunately resource_size(&crashk_res) returns 1 in this case.
This breaks the s390 implementation of crash_(un)map_reserved_pages().
To fix the problem the correct "old_size" is now calculated in
crash_shrink_memory(). "old_size is set to "0" if crashk_res is
not initialized. With this change crash_shrink_memory() will do nothing,
when "crashk_res" is not initialized. It will return "0" for
"echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
"echo [not zero] > /sys/kernel/kexec_crash_size".
In addition to that this patch also simplifies the "ret = -EINVAL"
vs. "ret = 0" logic as suggested by Simon Horman.
Cc: Simon Horman <horms@verge.net.au>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
---
kernel/kexec.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran
int crash_shrink_memory(unsigned long new_size)
{
int ret = 0;
- unsigned long start, end;
+ unsigned long start, end, old_size;
mutex_lock(&kexec_mutex);
@@ -1141,11 +1141,9 @@ int crash_shrink_memory(unsigned long ne
}
start = crashk_res.start;
end = crashk_res.end;
-
- if (new_size >= end - start + 1) {
- ret = -EINVAL;
- if (new_size == end - start + 1)
- ret = 0;
+ old_size = (end == 0) ? 0 : end - start + 1;
+ if (new_size >= old_size) {
+ ret = (new_size == old_size) ? 0 : -EINVAL;
goto unlock;
}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
2011-11-23 13:18 ` [PATCH v2] " Michael Holzheu
@ 2011-11-23 13:34 ` Dave Young
2011-11-23 13:46 ` Michael Holzheu
2011-11-23 15:01 ` Cong Wang
2011-11-24 0:10 ` Simon Horman
2 siblings, 1 reply; 8+ messages in thread
From: Dave Young @ 2011-11-23 13:34 UTC (permalink / raw)
To: holzheu
Cc: akpm, heiko.carstens, kexec, linux-kernel, Simon Horman,
Eric W. Biederman, schwidefsky, Vivek Goyal
On 11/23/2011 09:18 PM, Michael Holzheu wrote:
> From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
>
> Currently it is possible to set the crash_size via the sysfs
> /sys/kernel/kexec_crash_size even if no crash kernel memory has
> been defined with the "crashkernel" parameter. In this case
> "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
> Unfortunately resource_size(&crashk_res) returns 1 in this case.
> This breaks the s390 implementation of crash_(un)map_reserved_pages().
>
> To fix the problem the correct "old_size" is now calculated in
> crash_shrink_memory(). "old_size is set to "0" if crashk_res is
> not initialized. With this change crash_shrink_memory() will do nothing,
> when "crashk_res" is not initialized. It will return "0" for
> "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
> "echo [not zero] > /sys/kernel/kexec_crash_size".
>
> In addition to that this patch also simplifies the "ret = -EINVAL"
> vs. "ret = 0" logic as suggested by Simon Horman.
>
> Cc: Simon Horman <horms@verge.net.au>
> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
> ---
> kernel/kexec.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran
> int crash_shrink_memory(unsigned long new_size)
> {
> int ret = 0;
> - unsigned long start, end;
> + unsigned long start, end, old_size;
Sorry for jump in a little late, instead of introduce a new variable,
why not add something like:
if (!end)
return -EINVAL;
>
> mutex_lock(&kexec_mutex);
>
> @@ -1141,11 +1141,9 @@ int crash_shrink_memory(unsigned long ne
> }
> start = crashk_res.start;
> end = crashk_res.end;
> -
> - if (new_size >= end - start + 1) {
> - ret = -EINVAL;
> - if (new_size == end - start + 1)
> - ret = 0;
> + old_size = (end == 0) ? 0 : end - start + 1;
> + if (new_size >= old_size) {
> + ret = (new_size == old_size) ? 0 : -EINVAL;
> goto unlock;
> }
>
>
>
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
--
Thanks
Dave
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
2011-11-23 13:34 ` Dave Young
@ 2011-11-23 13:46 ` Michael Holzheu
2011-11-23 14:03 ` Dave Young
0 siblings, 1 reply; 8+ messages in thread
From: Michael Holzheu @ 2011-11-23 13:46 UTC (permalink / raw)
To: Dave Young
Cc: heiko.carstens, kexec, linux-kernel, Simon Horman,
Eric W. Biederman, schwidefsky, akpm, Vivek Goyal
Hi Dave,
On Wed, 2011-11-23 at 21:34 +0800, Dave Young wrote:
> On 11/23/2011 09:18 PM, Michael Holzheu wrote:
>
> > From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
> >
> > Currently it is possible to set the crash_size via the sysfs
> > /sys/kernel/kexec_crash_size even if no crash kernel memory has
> > been defined with the "crashkernel" parameter. In this case
> > "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
> > Unfortunately resource_size(&crashk_res) returns 1 in this case.
> > This breaks the s390 implementation of crash_(un)map_reserved_pages().
> >
> > To fix the problem the correct "old_size" is now calculated in
> > crash_shrink_memory(). "old_size is set to "0" if crashk_res is
> > not initialized. With this change crash_shrink_memory() will do nothing,
> > when "crashk_res" is not initialized. It will return "0" for
> > "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
> > "echo [not zero] > /sys/kernel/kexec_crash_size".
> >
> > In addition to that this patch also simplifies the "ret = -EINVAL"
> > vs. "ret = 0" logic as suggested by Simon Horman.
> >
> > Cc: Simon Horman <horms@verge.net.au>
> > Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
> > ---
> > kernel/kexec.c | 10 ++++------
> > 1 file changed, 4 insertions(+), 6 deletions(-)
> >
> > --- a/kernel/kexec.c
> > +++ b/kernel/kexec.c
> > @@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran
> > int crash_shrink_memory(unsigned long new_size)
> > {
> > int ret = 0;
> > - unsigned long start, end;
> > + unsigned long start, end, old_size;
>
>
> Sorry for jump in a little late, instead of introduce a new variable,
> why not add something like:
>
> if (!end)
> return -EINVAL;
If the crashkernel parameter is not set, "/sys/kernel/kexec_crash_size"
returns zero:
cat /sys/kernel/kexec_crash_size
0
So I think if we set it again to zero we should *not* return -EINVAL:
echo 0 > /sys/kernel/kexec_crash_size
--> Exit code should be zero in this case
Otherwise we would change the current behavior.
And besides of that, I think introducing the "old_size" variable makes
the code more readable.
Michael
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
2011-11-23 13:46 ` Michael Holzheu
@ 2011-11-23 14:03 ` Dave Young
0 siblings, 0 replies; 8+ messages in thread
From: Dave Young @ 2011-11-23 14:03 UTC (permalink / raw)
To: holzheu
Cc: heiko.carstens, kexec, linux-kernel, Simon Horman,
Eric W. Biederman, schwidefsky, akpm, Vivek Goyal
On 11/23/2011 09:46 PM, Michael Holzheu wrote:
> Hi Dave,
>
> On Wed, 2011-11-23 at 21:34 +0800, Dave Young wrote:
>> On 11/23/2011 09:18 PM, Michael Holzheu wrote:
>>
>>> From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
>>>
>>> Currently it is possible to set the crash_size via the sysfs
>>> /sys/kernel/kexec_crash_size even if no crash kernel memory has
>>> been defined with the "crashkernel" parameter. In this case
>>> "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
>>> Unfortunately resource_size(&crashk_res) returns 1 in this case.
>>> This breaks the s390 implementation of crash_(un)map_reserved_pages().
>>>
>>> To fix the problem the correct "old_size" is now calculated in
>>> crash_shrink_memory(). "old_size is set to "0" if crashk_res is
>>> not initialized. With this change crash_shrink_memory() will do nothing,
>>> when "crashk_res" is not initialized. It will return "0" for
>>> "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
>>> "echo [not zero] > /sys/kernel/kexec_crash_size".
>>>
>>> In addition to that this patch also simplifies the "ret = -EINVAL"
>>> vs. "ret = 0" logic as suggested by Simon Horman.
>>>
>>> Cc: Simon Horman <horms@verge.net.au>
>>> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
>>> ---
>>> kernel/kexec.c | 10 ++++------
>>> 1 file changed, 4 insertions(+), 6 deletions(-)
>>>
>>> --- a/kernel/kexec.c
>>> +++ b/kernel/kexec.c
>>> @@ -1131,7 +1131,7 @@ void __weak crash_free_reserved_phys_ran
>>> int crash_shrink_memory(unsigned long new_size)
>>> {
>>> int ret = 0;
>>> - unsigned long start, end;
>>> + unsigned long start, end, old_size;
>>
>>
>> Sorry for jump in a little late, instead of introduce a new variable,
>> why not add something like:
>>
>> if (!end)
>> return -EINVAL;
>
> If the crashkernel parameter is not set, "/sys/kernel/kexec_crash_size"
> returns zero:
>
> cat /sys/kernel/kexec_crash_size
> 0
>
> So I think if we set it again to zero we should *not* return -EINVAL:
Thanks, I missed this case. fair enough.
Reviewed-by: Dave Young <dyoung@redhat.com>
>
> echo 0 > /sys/kernel/kexec_crash_size
> --> Exit code should be zero in this case
>
> Otherwise we would change the current behavior.
>
> And besides of that, I think introducing the "old_size" variable makes
> the code more readable.
>
> Michael
>
>
--
Thanks
Dave
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
2011-11-23 13:18 ` [PATCH v2] " Michael Holzheu
2011-11-23 13:34 ` Dave Young
@ 2011-11-23 15:01 ` Cong Wang
2011-11-24 0:10 ` Simon Horman
2 siblings, 0 replies; 8+ messages in thread
From: Cong Wang @ 2011-11-23 15:01 UTC (permalink / raw)
To: holzheu
Cc: akpm, Simon Horman, heiko.carstens, kexec, linux-kernel,
Eric W. Biederman, schwidefsky, Vivek Goyal
On Wed, Nov 23, 2011 at 9:18 PM, Michael Holzheu
<holzheu@linux.vnet.ibm.com> wrote:
> From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
>
> Currently it is possible to set the crash_size via the sysfs
> /sys/kernel/kexec_crash_size even if no crash kernel memory has
> been defined with the "crashkernel" parameter. In this case
> "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
> Unfortunately resource_size(&crashk_res) returns 1 in this case.
> This breaks the s390 implementation of crash_(un)map_reserved_pages().
>
> To fix the problem the correct "old_size" is now calculated in
> crash_shrink_memory(). "old_size is set to "0" if crashk_res is
> not initialized. With this change crash_shrink_memory() will do nothing,
> when "crashk_res" is not initialized. It will return "0" for
> "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
> "echo [not zero] > /sys/kernel/kexec_crash_size".
>
> In addition to that this patch also simplifies the "ret = -EINVAL"
> vs. "ret = 0" logic as suggested by Simon Horman.
>
> Cc: Simon Horman <horms@verge.net.au>
> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Thanks.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] kdump: crashk_res init check for /sys/kernel/kexec_crash_size
2011-11-23 13:18 ` [PATCH v2] " Michael Holzheu
2011-11-23 13:34 ` Dave Young
2011-11-23 15:01 ` Cong Wang
@ 2011-11-24 0:10 ` Simon Horman
2 siblings, 0 replies; 8+ messages in thread
From: Simon Horman @ 2011-11-24 0:10 UTC (permalink / raw)
To: Michael Holzheu
Cc: akpm, heiko.carstens, kexec, linux-kernel, Eric W. Biederman,
schwidefsky, Vivek Goyal
On Wed, Nov 23, 2011 at 02:18:03PM +0100, Michael Holzheu wrote:
> From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
>
> Currently it is possible to set the crash_size via the sysfs
> /sys/kernel/kexec_crash_size even if no crash kernel memory has
> been defined with the "crashkernel" parameter. In this case
> "crashk_res" is not initialized and crashk_res.start = crashk_res.end = 0.
> Unfortunately resource_size(&crashk_res) returns 1 in this case.
> This breaks the s390 implementation of crash_(un)map_reserved_pages().
>
> To fix the problem the correct "old_size" is now calculated in
> crash_shrink_memory(). "old_size is set to "0" if crashk_res is
> not initialized. With this change crash_shrink_memory() will do nothing,
> when "crashk_res" is not initialized. It will return "0" for
> "echo 0 > /sys/kernel/kexec_crash_size" and -EINVAL for
> "echo [not zero] > /sys/kernel/kexec_crash_size".
>
> In addition to that this patch also simplifies the "ret = -EINVAL"
> vs. "ret = 0" logic as suggested by Simon Horman.
>
> Cc: Simon Horman <horms@verge.net.au>
> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Thanks Michael,
Reviewed-by: Simon Horman <horms@verge.net.au>
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2011-11-24 0:11 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-11-23 10:11 [PATCH] kdump: crashk_res init check for /sys/kernel/kexec_crash_size Michael Holzheu
2011-11-23 10:22 ` Simon Horman
2011-11-23 13:18 ` [PATCH v2] " Michael Holzheu
2011-11-23 13:34 ` Dave Young
2011-11-23 13:46 ` Michael Holzheu
2011-11-23 14:03 ` Dave Young
2011-11-23 15:01 ` Cong Wang
2011-11-24 0:10 ` Simon Horman
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).