Followup corrections to kexec STATUS patch v3

Followup corrections to kexec STATUS patch v3

[Eric DeVolder]

This contains the two corrections pointed out by Jan Beulich
for the kexec STATUS call just introduced.

Note: In kexec_status(), the use of test_bit() can also return
EPERM, so the return value from test_bit() must be checked to
ensure that kexec_status() always returns 0, 1 or -1, per the
public header description.

Note: My handling of the test_bit() scenario is to explicitly
check for return value of 1, so any value other than 1 causes
kexec_status to return 0.


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[PATCH] Put back blank line for readability purposes.

[Eric DeVolder]

This blank line was accidentally removed during
the insertion of the kexec_status() declarations.
---
 xen/include/public/kexec.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/include/public/kexec.h b/xen/include/public/kexec.h
index c200e8c..74ea981 100644
--- a/xen/include/public/kexec.h
+++ b/xen/include/public/kexec.h
@@ -240,6 +240,7 @@ typedef struct xen_kexec_status {
     uint8_t type;
 } xen_kexec_status_t;
 DEFINE_XEN_GUEST_HANDLE(xen_kexec_status_t);
+
 #else /* __XEN_INTERFACE_VERSION__ < 0x00040400 */
 
 #define KEXEC_CMD_kexec_load KEXEC_CMD_kexec_load_v1
-- 
2.7.4


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[PATCH] kexec: ensure kexec_status() always returns 0 or 1

[Eric DeVolder]

The use of test_bit() can also return EPERM, so the
return value from test_bit() must be checked to
ensure that kexec_status() always returns 0, 1 or
-1, per the public header description.
---
 xen/common/kexec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/common/kexec.c b/xen/common/kexec.c
index aa808cb..40b76d5 100644
--- a/xen/common/kexec.c
+++ b/xen/common/kexec.c
@@ -1182,7 +1182,7 @@ static int kexec_status(XEN_GUEST_HANDLE_PARAM(void) uarg)
     if ( kexec_load_get_bits(status.type, &base, &bit) )
         return -EINVAL;
 
-    return test_bit(bit, &kexec_flags);
+    return (test_bit(bit, &kexec_flags) == 1);
 }
 
 static int do_kexec_op_internal(unsigned long op,
-- 
2.7.4


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Re: Followup corrections to kexec STATUS patch v3

[Daniel Kiper]

On Wed, Jan 18, 2017 at 12:01:06PM -0600, Eric DeVolder wrote:
> This contains the two corrections pointed out by Jan Beulich
> for the kexec STATUS call just introduced.
>
> Note: In kexec_status(), the use of test_bit() can also return
> EPERM, so the return value from test_bit() must be checked to
> ensure that kexec_status() always returns 0, 1 or -1, per the
> public header description.
>
> Note: My handling of the test_bit() scenario is to explicitly
> check for return value of 1, so any value other than 1 causes
> kexec_status to return 0.

Great, however:
  - please use "git format-patch -n ..." to create patches,
  - first patch in the series should have [PATCH 0/3] in the subject,
  - both patches lack of your SOB.

Daniel

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