diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/hppa/internaltypes.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/hppa/internaltypes.h | 78 |
1 files changed, 0 insertions, 78 deletions
diff --git a/sysdeps/unix/sysv/linux/hppa/internaltypes.h b/sysdeps/unix/sysv/linux/hppa/internaltypes.h deleted file mode 100644 index 651ce2ee45..0000000000 --- a/sysdeps/unix/sysv/linux/hppa/internaltypes.h +++ /dev/null @@ -1,78 +0,0 @@ -#include_next <internaltypes.h> -#ifndef _INTERNAL_TYPES_H_HPPA_ -#define _INTERNAL_TYPES_H_HPPA_ 1 -#include <atomic.h> - -/* In GLIBC 2.10 HPPA switched from Linuxthreads to NPTL, and in order -to maintain ABI compatibility with pthread_cond_t, some care had to be -taken. - -The NPTL pthread_cond_t grew in size. When HPPA switched to NPTL, we -dropped the use of ldcw, and switched to the kernel helper routine for -compare-and-swap. This allowed HPPA to use the 4-word 16-byte aligned -lock words, and alignment words to store the additional pthread_cond_t -data. Once organized properly the new NPTL pthread_cond_t was 1 word -smaller than the Linuxthreads version. - -However, we were faced with the case that users may have initialized the -pthread_cond_t with PTHREAD_COND_INITIALIZER. In this case, the first -four words were set to one, and must be cleared before any NPTL code -used these words. - -We didn't want to use LDCW, because it continues to be a source of bugs -when applications memset pthread_cond_t to all zeroes by accident. This -works on all other architectures where lock words are unlocked at zero. -Remember that because of the semantics of LDCW, a locked word is set to -zero, and an unlocked word is set to 1. - -Instead we used atomic_compare_and_exchange_val_acq, but we couldn't use -this on any of the pthread_cond_t words, otherwise it might interfere -with the current operation of the structure. To solve this problem we -used the left over word. - -If the stucture was initialized by a legacy Linuxthread -PTHREAD_COND_INITIALIZER it contained a 1, and this indicates that the -structure requires zeroing for NPTL. The first thread to come upon a -pthread_cond_t with a 1 in the __initializer field, will -compare-and-swap the value, placing a 2 there which will cause all other -threads using the same pthread_cond_t to wait for the completion of the -initialization. Lastly, we use a store (with memory barrier) to change -__initializer from 2 to 0. Note that the store is strongly ordered, but -we use the PA 1.1 compatible form which is ",ma" with zero offset. - -In the future, when the application is recompiled with NPTL -PTHREAD_COND_INITIALIZER it will be a quick compare-and-swap, which -fails because __initializer is zero, and the structure will be used as -is correctly. */ - -#define cond_compat_clear(var) \ -({ \ - int tmp = 0; \ - var->__data.__lock = 0; \ - var->__data.__futex = 0; \ - var->__data.__mutex = NULL; \ - /* Clear __initializer last, to indicate initialization is done. */ \ - __asm__ __volatile__ ("stw,ma %1,0(%0)" \ - : : "r" (&var->__data.__initializer), "r" (tmp) : "memory"); \ -}) - -#define cond_compat_check_and_clear(var) \ -({ \ - int ret; \ - volatile int *value = &var->__data.__initializer; \ - if ((ret = atomic_compare_and_exchange_val_acq(value, 2, 1))) \ - { \ - if (ret == 1) \ - { \ - /* Initialize structure. */ \ - cond_compat_clear (var); \ - } \ - else \ - { \ - /* Yield until structure is initialized. */ \ - while (*value == 2) sched_yield (); \ - } \ - } \ -}) - -#endif |