Commit 3f4349dc authored by Kevin Wolf's avatar Kevin Wolf
Browse files

coroutine-ucontext: Help valgrind understand coroutines 



valgrind tends to get confused and report false positives when you
switch stacks and don't tell it about it.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 9e559533

configure

+20 −0
Original line number Diff line number Diff line
@@ -2870,6 +2870,22 @@ if compile_prog "" "" ; then 
    linux_magic_h=yes

fi



########################################

# check if we have valgrind/valgrind.h



valgrind_h=no

cat > $TMPC << EOF

#include <valgrind/valgrind.h>

#pragma GCC diagnostic ignored "-Wunused-but-set-variable"

int main(void) {

  VALGRIND_STACK_DEREGISTER(0);

  return 0;

}

EOF

if compile_prog "" "" ; then

    valgrind_h=yes

fi



########################################

# check if environ is declared
@@ -3379,6 +3395,10 @@ if test "$linux_magic_h" = "yes" ; then 
  echo "CONFIG_LINUX_MAGIC_H=y" >> $config_host_mak

fi



if test "$valgrind_h" = "yes" ; then

  echo "CONFIG_VALGRIND_H=y" >> $config_host_mak

fi



if test "$has_environ" = "yes" ; then

  echo "CONFIG_HAS_ENVIRON=y" >> $config_host_mak

fi

coroutine-ucontext.c

+28 −0
Original line number Diff line number Diff line
@@ -30,6 +30,10 @@ 
#include "qemu-common.h"

#include "qemu-coroutine-int.h"



#ifdef CONFIG_VALGRIND_H

#include <valgrind/valgrind.h>

#endif



enum {

    /* Maximum free pool size prevents holding too many freed coroutines */

    POOL_MAX_SIZE = 64,
@@ -43,6 +47,11 @@ typedef struct { 
    Coroutine base;

    void *stack;

    jmp_buf env;



#ifdef CONFIG_VALGRIND_H

    unsigned int valgrind_stack_id;

#endif



} CoroutineUContext;



/**
@@ -159,6 +168,11 @@ static Coroutine *coroutine_new(void) 
    uc.uc_stack.ss_size = stack_size;

    uc.uc_stack.ss_flags = 0;



#ifdef CONFIG_VALGRIND_H

    co->valgrind_stack_id =

        VALGRIND_STACK_REGISTER(co->stack, co->stack + stack_size);

#endif



    arg.p = co;



    makecontext(&uc, (void (*)(void))coroutine_trampoline,
@@ -185,6 +199,16 @@ Coroutine *qemu_coroutine_new(void) 
    return co;

}



#ifdef CONFIG_VALGRIND_H

/* Work around an unused variable in the valgrind.h macro... */

#pragma GCC diagnostic ignored "-Wunused-but-set-variable"

static inline void valgrind_stack_deregister(CoroutineUContext *co)

{

    VALGRIND_STACK_DEREGISTER(co->valgrind_stack_id);

}

#pragma GCC diagnostic error "-Wunused-but-set-variable"

#endif



void qemu_coroutine_delete(Coroutine *co_)

{

    CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
@@ -196,6 +220,10 @@ void qemu_coroutine_delete(Coroutine *co_) 
        return;

    }



#ifdef CONFIG_VALGRIND_H

    valgrind_stack_deregister(co);

#endif



    g_free(co->stack);

    g_free(co);

}