Add pthread_signal_safe_key_create.

13 files changed, 86 insertions, 18 deletions

diff --git a/README.google b/README.google
index da61b373ef..e817c6b277 100644
--- a/README.google
+++ b/README.google
@@ -245,3 +245,20 @@ sysdeps/generic/ldsodefs.h
   For b/4074041, add EXEC_ORIGIN support.
   Forward-ported from cl/56955623 and cl/59961863.
   (bmoses, google-local)
+
+nptl/Versions
+nptl/pthread_key_create.c
+nptl/sysdeps/pthread/pthread.h
+nptl/sysdeps/unix/sysv/linux/bits/local_lim.h
+nptl/sysdeps/unix/sysv/linux/powerpc/bits/local_lim.h
+nptl/sysdeps/unix/sysv/linux/sparc/bits/local_lim.h
+nptl/tst-key1.c
+nptl/tst-key4.c
+ports/sysdeps/unix/sysv/linux/aarch64/nptl/bits/local_lim.h
+ports/sysdeps/unix/sysv/linux/alpha/nptl/bits/local_lim.h
+ports/sysdeps/unix/sysv/linux/mips/nptl/bits/local_lim.h
+ports/sysdeps/unix/sysv/linux/tile/bits/local_lim.h
+  Add pthread_signal_safe_key_create.
+  Forward ported from cl/59612021, cl/59817832, and cl/59176280.
+  (ahh, google-local)
+
diff --git a/nptl/Versions b/nptl/Versions
index bb1127701e..1610909080 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -258,6 +258,7 @@ libpthread {
   }
 
   GLIBC_PRIVATE {
+    __google_pthread_signal_safe_key_create;
     __pthread_initialize_minimal;
     __pthread_clock_gettime; __pthread_clock_settime;
     __pthread_unwind; __pthread_get_minstack;
diff --git a/nptl/pthread_key_create.c b/nptl/pthread_key_create.c
index a22e446e18..49ad5d6fa9 100644
--- a/nptl/pthread_key_create.c
+++ b/nptl/pthread_key_create.c
@@ -18,33 +18,54 @@
 
 #include <errno.h>
 #include "pthreadP.h"
+#include <assert.h>
 #include <atomic.h>
 
+static int
+claim_key (pthread_key_t *key, void (*destr) (void *), size_t cnt)
+{
+  uintptr_t seq = __pthread_keys[cnt].seq;
+  if (KEY_UNUSED (seq) && KEY_USABLE (seq)
+      /* We found an unused slot.  Try to allocate it.  */
+      && ! atomic_compare_and_exchange_bool_acq (&__pthread_keys[cnt].seq,
+                                                 seq + 1, seq))
+    {
+      /* Remember the destructor.  */
+      __pthread_keys[cnt].destr = destr;
+
+      /* Return the key to the caller.  */
+      *key = cnt;
+      return 0;
+    }
+  return -1;
+}
 
 int
 __pthread_key_create (key, destr)
      pthread_key_t *key;
      void (*destr) (void *);
 {
-  /* Find a slot in __pthread_kyes which is unused.  */
-  for (size_t cnt = 0; cnt < PTHREAD_KEYS_MAX; ++cnt)
+  /* Find a slot in __pthread_keys which is unused.  */
+  for (size_t cnt = PTHREAD_SIGNAL_SAFE_KEYS_MAX; cnt < PTHREAD_KEYS_MAX; ++cnt)
+    {
+      if (claim_key (key, destr, cnt) == 0)
+        return 0;
+    }
+
+  return EAGAIN;
+}
+
+int __google_pthread_signal_safe_key_create (
+    pthread_key_t *key, void (*destr) (void *))
+{
+  /* Our implementation makes signal safe keys easy: they just have to
+     reside in the first (inline) block. */
+  assert (PTHREAD_SIGNAL_SAFE_KEYS_MAX <= PTHREAD_KEY_1STLEVEL_SIZE);
+  /* Find a slot in __pthread_keys which is unused.  */
+  for (size_t cnt = 0; cnt < PTHREAD_SIGNAL_SAFE_KEYS_MAX; ++cnt)
     {
-      uintptr_t seq = __pthread_keys[cnt].seq;
-
-      if (KEY_UNUSED (seq) && KEY_USABLE (seq)
-	  /* We found an unused slot.  Try to allocate it.  */
-	  && ! atomic_compare_and_exchange_bool_acq (&__pthread_keys[cnt].seq,
-						     seq + 1, seq))
-	{
-	  /* Remember the destructor.  */
-	  __pthread_keys[cnt].destr = destr;
-
-	  /* Return the key to the caller.  */
-	  *key = cnt;
-
-	  /* The call succeeded.  */
-	  return 0;
-	}
+      if (claim_key (key, destr, cnt) == 0)
+        return 0;
     }
 
   return EAGAIN;
diff --git a/nptl/sysdeps/pthread/pthread.h b/nptl/sysdeps/pthread/pthread.h
index 1e0c5dc937..3888596a74 100644
--- a/nptl/sysdeps/pthread/pthread.h
+++ b/nptl/sysdeps/pthread/pthread.h
@@ -1123,6 +1123,20 @@ extern int pthread_key_create (pthread_key_t *__key,
 			       void (*__destr_function) (void *))
      __THROW __nonnull ((1));
 
+/* Exactly as pthread_key_create, but returns an async-signal-safe key:
+   getspecific, setspecific, and key_delete are async-signal-safe when
+   used with the returned key. The number of signal_safe keys is *extremely*
+   limited (PTHREAD_SIGNAL_SAFE_KEY_MAX); you are highly recommended to use
+   pthread_key_create unless it's absolutely necessary.  This function
+   is async-signal-safe. */
+#if !defined(IS_IN_libpthread)
+__attribute__((weak))
+#endif
+extern int __google_pthread_signal_safe_key_create (pthread_key_t *__key,
+						    void (*__destr_function) (void *))
+    __THROW  __nonnull ((1));
+
+
 /* Destroy KEY.  */
 extern int pthread_key_delete (pthread_key_t __key) __THROW;
 
diff --git a/nptl/sysdeps/unix/sysv/linux/bits/local_lim.h b/nptl/sysdeps/unix/sysv/linux/bits/local_lim.h
index b802facd5d..13f2586a32 100644
--- a/nptl/sysdeps/unix/sysv/linux/bits/local_lim.h
+++ b/nptl/sysdeps/unix/sysv/linux/bits/local_lim.h
@@ -62,6 +62,7 @@
 #define _POSIX_THREAD_KEYS_MAX	128
 /* This is the value this implementation supports.  */
 #define PTHREAD_KEYS_MAX	1024
+#define PTHREAD_SIGNAL_SAFE_KEYS_MAX	4
 
 /* Controlling the iterations of destructors for thread-specific data.  */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS	4
diff --git a/nptl/sysdeps/unix/sysv/linux/powerpc/bits/local_lim.h b/nptl/sysdeps/unix/sysv/linux/powerpc/bits/local_lim.h
index e022226a5b..570dd223fa 100644
--- a/nptl/sysdeps/unix/sysv/linux/powerpc/bits/local_lim.h
+++ b/nptl/sysdeps/unix/sysv/linux/powerpc/bits/local_lim.h
@@ -62,6 +62,7 @@
 #define _POSIX_THREAD_KEYS_MAX	128
 /* This is the value this implementation supports.  */
 #define PTHREAD_KEYS_MAX	1024
+#define PTHREAD_SIGNAL_SAFE_KEYS_MAX	4
 
 /* Controlling the iterations of destructors for thread-specific data.  */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS	4
diff --git a/nptl/sysdeps/unix/sysv/linux/sparc/bits/local_lim.h b/nptl/sysdeps/unix/sysv/linux/sparc/bits/local_lim.h
index ad68f5060f..176025352b 100644
--- a/nptl/sysdeps/unix/sysv/linux/sparc/bits/local_lim.h
+++ b/nptl/sysdeps/unix/sysv/linux/sparc/bits/local_lim.h
@@ -62,6 +62,7 @@
 #define _POSIX_THREAD_KEYS_MAX	128
 /* This is the value this implementation supports.  */
 #define PTHREAD_KEYS_MAX	1024
+#define PTHREAD_SIGNAL_SAFE_KEYS_MAX	4
 
 /* Controlling the iterations of destructors for thread-specific data.  */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS	4
diff --git a/nptl/tst-key1.c b/nptl/tst-key1.c
index b40fffc33b..af5cb7e5cc 100644
--- a/nptl/tst-key1.c
+++ b/nptl/tst-key1.c
@@ -28,7 +28,11 @@ do_test (void)
 {
   int max;
 #ifdef PTHREAD_KEYS_MAX
+#ifdef PTHREAD_SIGNAL_SAFE_KEYS_MAX
+  max = PTHREAD_KEYS_MAX - PTHREAD_SIGNAL_SAFE_KEYS_MAX;
+#else
   max = PTHREAD_KEYS_MAX;
+#endif
 #else
   max = _POSIX_THREAD_KEYS_MAX;
 #endif
diff --git a/nptl/tst-key4.c b/nptl/tst-key4.c
index 9e65b59cae..d431c36366 100644
--- a/nptl/tst-key4.c
+++ b/nptl/tst-key4.c
@@ -24,7 +24,11 @@
 
 
 #ifdef PTHREAD_KEYS_MAX
+#ifdef PTHREAD_SIGNAL_SAFE_KEYS_MAX
+const int max = PTHREAD_KEYS_MAX - PTHREAD_SIGNAL_SAFE_KEYS_MAX;
+#else
 const int max = PTHREAD_KEYS_MAX;
+#endif
 #else
 const int max = _POSIX_THREAD_KEYS_MAX;
 #endif
diff --git a/ports/sysdeps/unix/sysv/linux/aarch64/nptl/bits/local_lim.h b/ports/sysdeps/unix/sysv/linux/aarch64/nptl/bits/local_lim.h
index 0b01c72de4..10f27b9ec2 100644
--- a/ports/sysdeps/unix/sysv/linux/aarch64/nptl/bits/local_lim.h
+++ b/ports/sysdeps/unix/sysv/linux/aarch64/nptl/bits/local_lim.h
@@ -63,6 +63,7 @@
 #define _POSIX_THREAD_KEYS_MAX	128
 /* This is the value this implementation supports.  */
 #define PTHREAD_KEYS_MAX	1024
+#define PTHREAD_SIGNAL_SAFE_KEYS_MAX	4
 
 /* Controlling the iterations of destructors for thread-specific data.  */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS	4
diff --git a/ports/sysdeps/unix/sysv/linux/alpha/nptl/bits/local_lim.h b/ports/sysdeps/unix/sysv/linux/alpha/nptl/bits/local_lim.h
index 950273e063..70e8665b0a 100644
--- a/ports/sysdeps/unix/sysv/linux/alpha/nptl/bits/local_lim.h
+++ b/ports/sysdeps/unix/sysv/linux/alpha/nptl/bits/local_lim.h
@@ -62,6 +62,7 @@
 #define _POSIX_THREAD_KEYS_MAX	128
 /* This is the value this implementation supports.  */
 #define PTHREAD_KEYS_MAX	1024
+#define PTHREAD_SIGNAL_SAFE_KEYS_MAX	4
 
 /* Controlling the iterations of destructors for thread-specific data.  */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS	4
diff --git a/ports/sysdeps/unix/sysv/linux/mips/nptl/bits/local_lim.h b/ports/sysdeps/unix/sysv/linux/mips/nptl/bits/local_lim.h
index 2366908d9c..32a6775f38 100644
--- a/ports/sysdeps/unix/sysv/linux/mips/nptl/bits/local_lim.h
+++ b/ports/sysdeps/unix/sysv/linux/mips/nptl/bits/local_lim.h
@@ -62,6 +62,7 @@
 #define _POSIX_THREAD_KEYS_MAX	128
 /* This is the value this implementation supports.  */
 #define PTHREAD_KEYS_MAX	1024
+#define PTHREAD_SIGNAL_SAFE_KEYS_MAX	4
 
 /* Controlling the iterations of destructors for thread-specific data.  */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS	4
diff --git a/ports/sysdeps/unix/sysv/linux/tile/bits/local_lim.h b/ports/sysdeps/unix/sysv/linux/tile/bits/local_lim.h
index 4e5605fd52..2f92153d93 100644
--- a/ports/sysdeps/unix/sysv/linux/tile/bits/local_lim.h
+++ b/ports/sysdeps/unix/sysv/linux/tile/bits/local_lim.h
@@ -62,6 +62,7 @@
 #define _POSIX_THREAD_KEYS_MAX	128
 /* This is the value this implementation supports.  */
 #define PTHREAD_KEYS_MAX	1024
+#define PTHREAD_SIGNAL_SAFE_KEYS_MAX	4
 
 /* Controlling the iterations of destructors for thread-specific data.  */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS	4