[1/4] nptl: Use internal low-level lock type for !IS_IN (libc)
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Commit Message
This avoids an ABI hazard (types changing between different modules
of glibc) without introducing linknamespace issues. In particular,
NSS modules now call __lll_lock_wait_private@@GLIBC_PRIVATE to wait
on internal locks (the unlock path is inlined and performs a direct
system call).
---
sysdeps/nptl/libc-lockP.h | 51 ++++-----------------------------------
1 file changed, 5 insertions(+), 46 deletions(-)
Comments
On 06/07/2021 14:22, Florian Weimer via Libc-alpha wrote:
> This avoids an ABI hazard (types changing between different modules
> of glibc) without introducing linknamespace issues. In particular,
> NSS modules now call __lll_lock_wait_private@@GLIBC_PRIVATE to wait
> on internal locks (the unlock path is inlined and performs a direct
> system call).
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> sysdeps/nptl/libc-lockP.h | 51 ++++-----------------------------------
> 1 file changed, 5 insertions(+), 46 deletions(-)
>
> diff --git a/sysdeps/nptl/libc-lockP.h b/sysdeps/nptl/libc-lockP.h
> index ef88a3e533..b66c938e44 100644
> --- a/sysdeps/nptl/libc-lockP.h
> +++ b/sysdeps/nptl/libc-lockP.h
> @@ -33,18 +33,8 @@
> #include <lowlevellock.h>
> #include <tls.h>
>
> -#if IS_IN (libpthread)
> -/* This gets us the declarations of the __pthread_* internal names,
> - and hidden_proto for them. */
> -# include <pthreadP.h>
> -#endif
> -
> /* Mutex type. */
> -#if !IS_IN (libc) && !IS_IN (libpthread)
> -typedef pthread_mutex_t __libc_lock_t;
> -#else
> typedef int __libc_lock_t;
> -#endif
> typedef struct { pthread_mutex_t mutex; } __rtld_lock_recursive_t;
> typedef pthread_rwlock_t __libc_rwlock_t;
>
> @@ -108,56 +98,25 @@ _Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0");
>
> /* Initialize the named lock variable, leaving it in a consistent, unlocked
> state. */
> -#if IS_IN (libc) || IS_IN (libpthread)
> -# define __libc_lock_init(NAME) \
> - ((void) ((NAME) = LLL_LOCK_INITIALIZER))
> -#else
> -# define __libc_lock_init(NAME) __pthread_mutex_init (&(NAME))
> -#endif
> +#define __libc_lock_init(NAME) ((void) ((NAME) = LLL_LOCK_INITIALIZER))
> #define __libc_rwlock_init(NAME) __pthread_rwlock_init (&(NAME), NULL)
>
> /* Finalize the named lock variable, which must be locked. It cannot be
> used again until __libc_lock_init is called again on it. This must be
> called on a lock variable before the containing storage is reused. */
> -#if IS_IN (libc) || IS_IN (libpthread)
> -# define __libc_lock_fini(NAME) ((void) 0)
> -#else
> -# define __libc_lock_fini(NAME) __pthread_mutex_destroy (&(NAME))
> -#endif
> +#define __libc_lock_fini(NAME) ((void) 0)
> #define __libc_rwlock_fini(NAME) ((void) 0)
>
> /* Lock the named lock variable. */
> -#if IS_IN (libc) || IS_IN (libpthread)
> -# ifndef __libc_lock_lock
> -# define __libc_lock_lock(NAME) \
> - ({ lll_lock (NAME, LLL_PRIVATE); 0; })
> -# endif
> -#else
> -# undef __libc_lock_lock
> -# define __libc_lock_lock(NAME) __pthread_mutex_lock (&(NAME))
> -#endif
> +#define __libc_lock_lock(NAME) ({ lll_lock (NAME, LLL_PRIVATE); 0; })
> #define __libc_rwlock_rdlock(NAME) __pthread_rwlock_rdlock (&(NAME))
> #define __libc_rwlock_wrlock(NAME) __pthread_rwlock_wrlock (&(NAME))
>
> /* Try to lock the named lock variable. */
> -#if IS_IN (libc) || IS_IN (libpthread)
> -# ifndef __libc_lock_trylock
> -# define __libc_lock_trylock(NAME) \
> - lll_trylock (NAME)
> -# endif
> -#else
> -# undef __libc_lock_trylock
> -# define __libc_lock_trylock(NAME) \
> - __libc_maybe_call (__pthread_mutex_trylock, (&(NAME)), 0)
> -#endif
> +#define __libc_lock_trylock(NAME) lll_trylock (NAME)
>
> /* Unlock the named lock variable. */
> -#if IS_IN (libc) || IS_IN (libpthread)
> -# define __libc_lock_unlock(NAME) \
> - lll_unlock (NAME, LLL_PRIVATE)
> -#else
> -# define __libc_lock_unlock(NAME) __pthread_mutex_unlock (&(NAME))
> -#endif
> +#define __libc_lock_unlock(NAME) lll_unlock (NAME, LLL_PRIVATE)
> #define __libc_rwlock_unlock(NAME) __pthread_rwlock_unlock (&(NAME))
>
> #if IS_IN (rtld)
>
@@ -33,18 +33,8 @@
#include <lowlevellock.h>
#include <tls.h>
-#if IS_IN (libpthread)
-/* This gets us the declarations of the __pthread_* internal names,
- and hidden_proto for them. */
-# include <pthreadP.h>
-#endif
-
/* Mutex type. */
-#if !IS_IN (libc) && !IS_IN (libpthread)
-typedef pthread_mutex_t __libc_lock_t;
-#else
typedef int __libc_lock_t;
-#endif
typedef struct { pthread_mutex_t mutex; } __rtld_lock_recursive_t;
typedef pthread_rwlock_t __libc_rwlock_t;
@@ -108,56 +98,25 @@ _Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0");
/* Initialize the named lock variable, leaving it in a consistent, unlocked
state. */
-#if IS_IN (libc) || IS_IN (libpthread)
-# define __libc_lock_init(NAME) \
- ((void) ((NAME) = LLL_LOCK_INITIALIZER))
-#else
-# define __libc_lock_init(NAME) __pthread_mutex_init (&(NAME))
-#endif
+#define __libc_lock_init(NAME) ((void) ((NAME) = LLL_LOCK_INITIALIZER))
#define __libc_rwlock_init(NAME) __pthread_rwlock_init (&(NAME), NULL)
/* Finalize the named lock variable, which must be locked. It cannot be
used again until __libc_lock_init is called again on it. This must be
called on a lock variable before the containing storage is reused. */
-#if IS_IN (libc) || IS_IN (libpthread)
-# define __libc_lock_fini(NAME) ((void) 0)
-#else
-# define __libc_lock_fini(NAME) __pthread_mutex_destroy (&(NAME))
-#endif
+#define __libc_lock_fini(NAME) ((void) 0)
#define __libc_rwlock_fini(NAME) ((void) 0)
/* Lock the named lock variable. */
-#if IS_IN (libc) || IS_IN (libpthread)
-# ifndef __libc_lock_lock
-# define __libc_lock_lock(NAME) \
- ({ lll_lock (NAME, LLL_PRIVATE); 0; })
-# endif
-#else
-# undef __libc_lock_lock
-# define __libc_lock_lock(NAME) __pthread_mutex_lock (&(NAME))
-#endif
+#define __libc_lock_lock(NAME) ({ lll_lock (NAME, LLL_PRIVATE); 0; })
#define __libc_rwlock_rdlock(NAME) __pthread_rwlock_rdlock (&(NAME))
#define __libc_rwlock_wrlock(NAME) __pthread_rwlock_wrlock (&(NAME))
/* Try to lock the named lock variable. */
-#if IS_IN (libc) || IS_IN (libpthread)
-# ifndef __libc_lock_trylock
-# define __libc_lock_trylock(NAME) \
- lll_trylock (NAME)
-# endif
-#else
-# undef __libc_lock_trylock
-# define __libc_lock_trylock(NAME) \
- __libc_maybe_call (__pthread_mutex_trylock, (&(NAME)), 0)
-#endif
+#define __libc_lock_trylock(NAME) lll_trylock (NAME)
/* Unlock the named lock variable. */
-#if IS_IN (libc) || IS_IN (libpthread)
-# define __libc_lock_unlock(NAME) \
- lll_unlock (NAME, LLL_PRIVATE)
-#else
-# define __libc_lock_unlock(NAME) __pthread_mutex_unlock (&(NAME))
-#endif
+#define __libc_lock_unlock(NAME) lll_unlock (NAME, LLL_PRIVATE)
#define __libc_rwlock_unlock(NAME) __pthread_rwlock_unlock (&(NAME))
#if IS_IN (rtld)