1.0.0.31: pthread-futex: another pthread back-end of mutex

[sbcl.git] / src / runtime / linux-os.c

diff --git a/src/runtime/linux-os.c b/src/runtime/linux-os.c
index 2b1dd25..4c6ef83 100644 (file)
--- a/src/runtime/linux-os.c
+++ b/src/runtime/linux-os.c
@@ -34,8 +34,10 @@
 #include "runtime.h"
 #include "genesis/static-symbols.h"
 #include "genesis/fdefn.h"
+
 #include <sys/socket.h>
 #include <sys/utsname.h>
+#include <errno.h>
 
 #include <sys/types.h>
 #include <signal.h>
@@ -60,7 +62,7 @@ int personality (unsigned long);
 
 size_t os_vm_page_size;
 
-#ifdef LISP_FEATURE_SB_THREAD
+#if defined(LISP_FEATURE_SB_THREAD) && !defined(LISP_FEATURE_SB_LUTEX) && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
 #include <sys/syscall.h>
 #include <unistd.h>
 #include <errno.h>
@@ -82,7 +84,18 @@ static inline int sys_futex (void *futex, int op, int val, struct timespec *rel)
 int
 futex_wait(int *lock_word, int oldval)
 {
-    int t= sys_futex(lock_word,FUTEX_WAIT,oldval, 0);
+    int t;
+  again:
+    t = sys_futex(lock_word,FUTEX_WAIT,oldval, 0);
+
+    /* Interrupted FUTEX_WAIT calls may return early.
+     *
+     * If someone manages to wake the futex while we're spinning
+     * around it, we will just return with -1 and errno EWOULDBLOCK,
+     * because the value has changed, so that's ok. */
+    if (t != 0 && errno == EINTR)
+        goto again;
+
     return t;
 }
 
@@ -95,6 +108,20 @@ futex_wake(int *lock_word, int n)
 
 \f
 int linux_sparc_siginfo_bug = 0;
+
+/* This variable was in real use for a few months, basically for
+ * storing autodetected information about whether the Linux
+ * installation was recent enough to support SBCL threads, and make
+ * some run-time decisions based on that. But this turned out to be
+ * unstable, so now we just flat-out refuse to start on the old installations
+ * when thread support has been compiled in.
+ *
+ * Unfortunately, in the meanwhile Slime started depending on this
+ * variable for deciding which communication style to use. So even
+ * though this variable looks unused, it shouldn't be deleted until
+ * it's no longer used in the versions of Slime that people are
+ * likely to download first. -- JES, 2006-06-07
+ */
 int linux_no_threads_p = 0;
 
 #ifdef LISP_FEATURE_SB_THREAD
@@ -118,7 +145,7 @@ os_init(char *argv[], char *envp[])
 {
     /* Conduct various version checks: do we have enough mmap(), is
      * this a sparc running 2.2, can we do threads? */
-#ifdef LISP_FEATURE_SB_THREAD
+#if defined(LISP_FEATURE_SB_THREAD) && !defined(LISP_FEATURE_SB_LUTEX) && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
     int *futex=0;
 #endif
     struct utsname name;
@@ -144,12 +171,14 @@ os_init(char *argv[], char *envp[])
 #endif
     }
 #ifdef LISP_FEATURE_SB_THREAD
+#if !defined(LISP_FEATURE_SB_LUTEX) && !defined(LISP_FEATURE_SB_PTHREAD_FUTEX)
     futex_wait(futex,-1);
     if(errno==ENOSYS) {
        lose("This version of SBCL is compiled with threading support, but your kernel\n"
             "is too old to support this. Please use a more recent kernel or\n"
             "a version of SBCL without threading support.\n");
     }
+#endif
     if(! isnptl()) {
        lose("This version of SBCL only works correctly with the NPTL threading\n"
             "library. Please use a newer glibc, use an older SBCL, or stop using\n"
@@ -284,7 +313,14 @@ void
 os_protect(os_vm_address_t address, os_vm_size_t length, os_vm_prot_t prot)
 {
     if (mprotect(address, length, prot) == -1) {
-        perror("mprotect");
+        if (errno == ENOMEM) {
+            lose("An mprotect call failed with ENOMEM. This probably means that the maximum amount\n"
+                 "of separate memory mappings was exceeded. To fix the problem, either increase\n"
+                 "the maximum with e.g. 'echo 262144 > /proc/sys/vm/max_map_count' or recompile\n"
+                 "SBCL with a larger value for GENCGC-PAGE-SIZE in 'src/target/parms.lisp'.");
+        } else {
+            perror("mprotect");
+        }
     }
 }
 \f
@@ -352,7 +388,7 @@ sigsegv_handler(int signal, siginfo_t *info, void* void_context)
 #endif
         if (!handle_guard_page_triggered(context, addr))
 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
-            arrange_return_to_lisp_function(context, SymbolFunction(MEMORY_FAULT_ERROR));
+            lisp_memory_fault_error(context, addr);
 #else
             interrupt_handle_now(signal, info, context);
 #endif
@@ -370,3 +406,18 @@ os_install_interrupt_handlers(void)
                                                  sig_stop_for_gc_handler);
 #endif
 }
+
+char *
+os_get_runtime_executable_path()
+{
+    char path[PATH_MAX + 1];
+    int size;
+
+    size = readlink("/proc/self/exe", path, sizeof(path)-1);
+    if (size < 0)
+        return NULL;
+    else
+        path[size] = '\0';
+
+    return copied_string(path);
+}