hw/pci: removed 'rootbus nr is 0' assumption from qmp_pci_query

[qemu.git] / coroutine-ucontext.c

diff --git a/coroutine-ucontext.c b/coroutine-ucontext.c
index 2ed703a3ed7f510708c3fb80211132c76d065551..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 <stdlib.h>
 #include <setjmp.h>
 #include <stdint.h>

-#include <pthread.h>

 #include <ucontext.h>
 #include "qemu-common.h"
 #include "block/coroutine_int.h"
 #include <ucontext.h>
 #include "qemu-common.h"
 #include "block/coroutine_int.h"


@@ -34,19 +33,10 @@
 #include <valgrind/valgrind.h>
 #endif
 
 #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;
 typedef struct {
     Coroutine base;
     void *stack;

-    jmp_buf env;
+    sigjmp_buf env;

 
 #ifdef CONFIG_VALGRIND_H
     unsigned int valgrind_stack_id;
 
 #ifdef CONFIG_VALGRIND_H
     unsigned int valgrind_stack_id;


@@ -57,15 +47,8 @@ typedef struct {
 /**
  * Per-thread coroutine bookkeeping
  */
 /**
  * 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
 
 /*
  * va_args to makecontext() must be type 'int', so passing


@@ -77,47 +60,6 @@ union cc_arg {
     int i[2];
 };
 
     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;
 static void coroutine_trampoline(int i0, int i1)
 {
     union cc_arg arg;


@@ -130,8 +72,8 @@ static void coroutine_trampoline(int i0, int i1)
     co = &self->base;
 
     /* Initialize longjmp environment and switch back the caller */
     co = &self->base;
 
     /* Initialize longjmp environment and switch back the caller */

-    if (!setjmp(self->env)) {
-        longjmp(*(jmp_buf *)co->entry_arg, 1);
+    if (!sigsetjmp(self->env, 0)) {
+        siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);

     }
 
     while (true) {
     }
 
     while (true) {


@@ -140,19 +82,20 @@ 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;
     ucontext_t old_uc, uc;
 {
     const size_t stack_size = 1 << 20;
     CoroutineUContext *co;
     ucontext_t old_uc, uc;

-    jmp_buf old_env;
+    sigjmp_buf old_env;

     union cc_arg arg = {0};
 
     union cc_arg arg = {0};
 

-    /* The ucontext functions preserve signal masks which incurs a system call
-     * overhead.  setjmp()/longjmp() does not preserve signal masks but only
-     * works on the current stack.  Since we need a way to create and switch to
-     * a new stack, use the ucontext functions for that but setjmp()/longjmp()
-     * for everything else.
+    /* The ucontext functions preserve signal masks which incurs a
+     * system call overhead.  sigsetjmp(buf, 0)/siglongjmp() does not
+     * preserve signal masks but only works on the current stack.
+     * Since we need a way to create and switch to a new stack, use
+     * the ucontext functions for that but sigsetjmp()/siglongjmp() for
+     * everything else.

      */
 
     if (getcontext(&uc) == -1) {
      */
 
     if (getcontext(&uc) == -1) {


@@ -178,38 +121,25 @@ static Coroutine *coroutine_new(void)
     makecontext(&uc, (void (*)(void))coroutine_trampoline,
                 2, arg.i[0], arg.i[1]);
 
     makecontext(&uc, (void (*)(void))coroutine_trampoline,
                 2, arg.i[0], arg.i[1]);
 

-    /* swapcontext() in, longjmp() back out */
-    if (!setjmp(old_env)) {
+    /* swapcontext() in, siglongjmp() back out */
+    if (!sigsetjmp(old_env, 0)) {

         swapcontext(&old_uc, &uc);
     }
     return &co->base;
 }
 
         swapcontext(&old_uc, &uc);
     }
     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_VALGRIND_H

-#ifdef CONFIG_PRAGMA_DISABLE_UNUSED_BUT_SET
+#ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE

 /* Work around an unused variable in the valgrind.h macro... */
 /* 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)
 {
     VALGRIND_STACK_DEREGISTER(co->valgrind_stack_id);
 }
 #pragma GCC diagnostic ignored "-Wunused-but-set-variable"
 #endif
 static inline void valgrind_stack_deregister(CoroutineUContext *co)
 {
     VALGRIND_STACK_DEREGISTER(co->valgrind_stack_id);
 }

-#ifdef CONFIG_PRAGMA_DISABLE_UNUSED_BUT_SET
-#pragma GCC diagnostic error "-Wunused-but-set-variable"
+#ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE
+#pragma GCC diagnostic pop

 #endif
 #endif
 
 #endif
 #endif
 


@@ -217,13 +147,6 @@ void qemu_coroutine_delete(Coroutine *co_)
 {
     CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, 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
 #ifdef CONFIG_VALGRIND_H
     valgrind_stack_deregister(co);
 #endif


@@ -232,33 +155,40 @@ void qemu_coroutine_delete(Coroutine *co_)
     g_free(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_);
 {
     CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
     CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);

-    CoroutineThreadState *s = coroutine_get_thread_state();

     int ret;
 
     int ret;
 

-    s->current = to_;
+    current = to_;

 
 

-    ret = setjmp(from->env);
+    ret = sigsetjmp(from->env, 0);

     if (ret == 0) {
     if (ret == 0) {

-        longjmp(to->env, action);
+        siglongjmp(to->env, action);

     }
     return ret;
 }
 
 Coroutine *qemu_coroutine_self(void)
 {
     }
     return ret;
 }
 
 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)
 {
 }
 
 bool qemu_in_coroutine(void)
 {

-    CoroutineThreadState *s = pthread_getspecific(thread_state_key);
-
-    return s && s->current->caller;
+    return current && current->caller;

 }
 }