xen/pt: Use xen_host_pci_get_[byte|word] instead of dev.config

[mirror_qemu.git] / coroutine-ucontext.c

diff --git a/coroutine-ucontext.c b/coroutine-ucontext.c
index bd20e384b7b7c2339d712d5c8f23552b7d90466b..259fcb48a42ab7346afac0708cfc6506add58675 100644 (file)
--- a/coroutine-ucontext.c
+++ b/coroutine-ucontext.c
@@ -25,7 +25,6 @@
 #include <stdlib.h>
 #include <setjmp.h>
 #include <stdint.h>
-#include <pthread.h>
 #include <ucontext.h>
 #include "qemu-common.h"
 #include "block/coroutine_int.h"
@@ -34,15 +33,6 @@
 #include <valgrind/valgrind.h>
 #endif
 
-enum {
-    /* Maximum free pool size prevents holding too many freed coroutines */
-    POOL_MAX_SIZE = 64,
-};
-
-/** Free list to speed up creation */
-static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
-static unsigned int pool_size;
-
 typedef struct {
     Coroutine base;
     void *stack;
@@ -57,15 +47,8 @@ typedef struct {
 /**
  * Per-thread coroutine bookkeeping
  */
-typedef struct {
-    /** Currently executing coroutine */
-    Coroutine *current;
-
-    /** The default coroutine */
-    CoroutineUContext leader;
-} CoroutineThreadState;
-
-static pthread_key_t thread_state_key;
+static __thread CoroutineUContext leader;
+static __thread Coroutine *current;
 
 /*
  * va_args to makecontext() must be type 'int', so passing
@@ -77,47 +60,6 @@ union cc_arg {
     int i[2];
 };
 
-static CoroutineThreadState *coroutine_get_thread_state(void)
-{
-    CoroutineThreadState *s = pthread_getspecific(thread_state_key);
-
-    if (!s) {
-        s = g_malloc0(sizeof(*s));
-        s->current = &s->leader.base;
-        pthread_setspecific(thread_state_key, s);
-    }
-    return s;
-}
-
-static void qemu_coroutine_thread_cleanup(void *opaque)
-{
-    CoroutineThreadState *s = opaque;
-
-    g_free(s);
-}
-
-static void __attribute__((destructor)) coroutine_cleanup(void)
-{
-    Coroutine *co;
-    Coroutine *tmp;
-
-    QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) {
-        g_free(DO_UPCAST(CoroutineUContext, base, co)->stack);
-        g_free(co);
-    }
-}
-
-static void __attribute__((constructor)) coroutine_init(void)
-{
-    int ret;
-
-    ret = pthread_key_create(&thread_state_key, qemu_coroutine_thread_cleanup);
-    if (ret != 0) {
-        fprintf(stderr, "unable to create leader key: %s\n", strerror(errno));
-        abort();
-    }
-}
-
 static void coroutine_trampoline(int i0, int i1)
 {
     union cc_arg arg;
@@ -140,7 +82,7 @@ static void coroutine_trampoline(int i0, int i1)
     }
 }
 
-static Coroutine *coroutine_new(void)
+Coroutine *qemu_coroutine_new(void)
 {
     const size_t stack_size = 1 << 20;
     CoroutineUContext *co;
@@ -186,23 +128,10 @@ static Coroutine *coroutine_new(void)
     return &co->base;
 }
 
-Coroutine *qemu_coroutine_new(void)
-{
-    Coroutine *co;
-
-    co = QSLIST_FIRST(&pool);
-    if (co) {
-        QSLIST_REMOVE_HEAD(&pool, pool_next);
-        pool_size--;
-    } else {
-        co = coroutine_new();
-    }
-    return co;
-}
-
 #ifdef CONFIG_VALGRIND_H
 #ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE
 /* Work around an unused variable in the valgrind.h macro... */
+#pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wunused-but-set-variable"
 #endif
 static inline void valgrind_stack_deregister(CoroutineUContext *co)
@@ -210,7 +139,7 @@ static inline void valgrind_stack_deregister(CoroutineUContext *co)
     VALGRIND_STACK_DEREGISTER(co->valgrind_stack_id);
 }
 #ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE
-#pragma GCC diagnostic error "-Wunused-but-set-variable"
+#pragma GCC diagnostic pop
 #endif
 #endif
 
@@ -218,13 +147,6 @@ void qemu_coroutine_delete(Coroutine *co_)
 {
     CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
 
-    if (pool_size < POOL_MAX_SIZE) {
-        QSLIST_INSERT_HEAD(&pool, &co->base, pool_next);
-        co->base.caller = NULL;
-        pool_size++;
-        return;
-    }
-
 #ifdef CONFIG_VALGRIND_H
     valgrind_stack_deregister(co);
 #endif
@@ -233,15 +155,23 @@ void qemu_coroutine_delete(Coroutine *co_)
     g_free(co);
 }
 
-CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
-                                      CoroutineAction action)
+/* This function is marked noinline to prevent GCC from inlining it
+ * into coroutine_trampoline(). If we allow it to do that then it
+ * hoists the code to get the address of the TLS variable "current"
+ * out of the while() loop. This is an invalid transformation because
+ * the sigsetjmp() call may be called when running thread A but
+ * return in thread B, and so we might be in a different thread
+ * context each time round the loop.
+ */
+CoroutineAction __attribute__((noinline))
+qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
+                      CoroutineAction action)
 {
     CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
     CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);
-    CoroutineThreadState *s = coroutine_get_thread_state();
     int ret;
 
-    s->current = to_;
+    current = to_;
 
     ret = sigsetjmp(from->env, 0);
     if (ret == 0) {
@@ -252,14 +182,13 @@ CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
 
 Coroutine *qemu_coroutine_self(void)
 {
-    CoroutineThreadState *s = coroutine_get_thread_state();
-
-    return s->current;
+    if (!current) {
+        current = &leader.base;
+    }
+    return current;
 }
 
 bool qemu_in_coroutine(void)
 {
-    CoroutineThreadState *s = pthread_getspecific(thread_state_key);
-
-    return s && s->current->caller;
+    return current && current->caller;
 }