Re: svn commit: r357728 - head/sys/sys

2020-02-10 Thread Gleb Smirnoff 
On Mon, Feb 10, 2020 at 01:52:26PM +, Mateusz Guzik wrote:
M> Author: mjg
M> Date: Mon Feb 10 13:52:25 2020
M> New Revision: 357728
M> URL: https://svnweb.freebsd.org/changeset/base/357728
M> 
M> Log:
M>   Tidy up zpcpu_replace*
M>   
M>   - only compute the target address once
M>   - remove spurious type casting, zpcpu_get already return the correct type
M>   
M>   While here add missing newlines to other routines.
M> 
M> Modified:
M>   head/sys/sys/pcpu.h
M> 
M> Modified: head/sys/sys/pcpu.h
M> 
==
M> --- head/sys/sys/pcpu.h  Mon Feb 10 13:24:14 2020(r357727)
M> +++ head/sys/sys/pcpu.h  Mon Feb 10 13:52:25 2020(r357728)
M> @@ -245,32 +245,41 @@ extern struct pcpu *cpuid_to_pcpu[];
M>   * If you need atomicity use xchg.
M>   * */
M>  #define zpcpu_replace(base, val) ({ \
M> -__typeof(val) _old = *(__typeof(base))zpcpu_get(base);  \
M> -*(__typeof(val) *)zpcpu_get(base) = val;\
M> +__typeof(val) *_ptr = zpcpu_get(base);  \
M> +__typeof(val) _old; \
M> +\
M> +_old = *_ptr;   \
M> +*_ptr = val;\
M>  _old;   \
M>  })

I think this function must have only protected variant that asserts
that curthread->td_critnest is on.

zpcpu_get() sometimes can be used without critical section, when we
are fine with getting a value from a different CPU.

However, can't imagine a situation where migrating during a replace
operation is acceptable.

-- 
Gleb Smirnoff
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Re: svn commit: r357728 - head/sys/sys

2020-02-10 Thread Pedro Giffuni 

Hi;

On 10/02/2020 08:52, Mateusz Guzik wrote:

Author: mjg
Date: Mon Feb 10 13:52:25 2020
New Revision: 357728
URL: https://svnweb.freebsd.org/changeset/base/357728

Log:
   Tidy up zpcpu_replace*
   
   - only compute the target address once

   - remove spurious type casting, zpcpu_get already return the correct type
   
   While here add missing newlines to other routines.


Modified:
   head/sys/sys/pcpu.h


For the record, this file (and many others), uses a space after #define, 
when we should be using a tab to conform with style(9). One of the many 
lessons from bde.


I have a huge patch to fix those, which I won't commit because it wouldl 
obliterate all VCS annotations.


Pedro.



Modified: head/sys/sys/pcpu.h
==
--- head/sys/sys/pcpu.h Mon Feb 10 13:24:14 2020(r357727)
+++ head/sys/sys/pcpu.h Mon Feb 10 13:52:25 2020(r357728)
@@ -245,32 +245,41 @@ extern struct pcpu *cpuid_to_pcpu[];
   * If you need atomicity use xchg.
   * */
  #define zpcpu_replace(base, val) ({   \
-   __typeof(val) _old = *(__typeof(base))zpcpu_get(base);  \
-   *(__typeof(val) *)zpcpu_get(base) = val;\
+   __typeof(val) *_ptr = zpcpu_get(base);  \
+   __typeof(val) _old; \
+   \
+   _old = *_ptr;   \
+   *_ptr = val;\
_old;   \
  })
  
  #define zpcpu_replace_cpu(base, val, cpu) ({\

-   __typeof(val) _old = *(__typeof(base))zpcpu_get_cpu(base, cpu); \
-   *(__typeof(val) *)zpcpu_get_cpu(base, cpu) = val;   \
+   __typeof(val) *_ptr = zpcpu_get_cpu(base, cpu); \
+   __typeof(val) _old; \
+   \
+   _old = *_ptr;   \
+   *_ptr = val;\
_old;   \
  })
  
  #define zpcpu_set_protected(base, val) ({\

MPASS(curthread->td_critnest > 0);\
__typeof(val) *_ptr = zpcpu_get(base);  \
+   \
*_ptr = (val);  \
  })
  
  #define zpcpu_add_protected(base, val) ({\

MPASS(curthread->td_critnest > 0);\
__typeof(val) *_ptr = zpcpu_get(base);  \
+   \
*_ptr += (val); \
  })
  
  #define zpcpu_sub_protected(base, val) ({\

MPASS(curthread->td_critnest > 0);\
__typeof(val) *_ptr = zpcpu_get(base);  \
+   \
*_ptr -= (val); \
  })
  

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svn commit: r357728 - head/sys/sys

2020-02-10 Thread Mateusz Guzik 
Author: mjg
Date: Mon Feb 10 13:52:25 2020
New Revision: 357728
URL: https://svnweb.freebsd.org/changeset/base/357728

Log:
  Tidy up zpcpu_replace*
  
  - only compute the target address once
  - remove spurious type casting, zpcpu_get already return the correct type
  
  While here add missing newlines to other routines.

Modified:
  head/sys/sys/pcpu.h

Modified: head/sys/sys/pcpu.h
==
--- head/sys/sys/pcpu.h Mon Feb 10 13:24:14 2020(r357727)
+++ head/sys/sys/pcpu.h Mon Feb 10 13:52:25 2020(r357728)
@@ -245,32 +245,41 @@ extern struct pcpu *cpuid_to_pcpu[];
  * If you need atomicity use xchg.
  * */
 #define zpcpu_replace(base, val) ({\
-   __typeof(val) _old = *(__typeof(base))zpcpu_get(base);  \
-   *(__typeof(val) *)zpcpu_get(base) = val;\
+   __typeof(val) *_ptr = zpcpu_get(base);  \
+   __typeof(val) _old; \
+   \
+   _old = *_ptr;   \
+   *_ptr = val;\
_old;   \
 })
 
 #define zpcpu_replace_cpu(base, val, cpu) ({   \
-   __typeof(val) _old = *(__typeof(base))zpcpu_get_cpu(base, cpu); \
-   *(__typeof(val) *)zpcpu_get_cpu(base, cpu) = val;   \
+   __typeof(val) *_ptr = zpcpu_get_cpu(base, cpu); \
+   __typeof(val) _old; \
+   \
+   _old = *_ptr;   \
+   *_ptr = val;\
_old;   \
 })
 
 #define zpcpu_set_protected(base, val) ({  \
MPASS(curthread->td_critnest > 0);  \
__typeof(val) *_ptr = zpcpu_get(base);  \
+   \
*_ptr = (val);  \
 })
 
 #define zpcpu_add_protected(base, val) ({  \
MPASS(curthread->td_critnest > 0);  \
__typeof(val) *_ptr = zpcpu_get(base);  \
+   \
*_ptr += (val); \
 })
 
 #define zpcpu_sub_protected(base, val) ({  \
MPASS(curthread->td_critnest > 0);  \
__typeof(val) *_ptr = zpcpu_get(base);  \
+   \
*_ptr -= (val); \
 })
 
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