# HG changeset patch
# User root@xxxxxxxxxxxxxxxxxxxxx
# Date 1290077186 18000
# Node ID 3de336d9c113359203885ca6cf6360e5250dfe82
# Parent 61797efad6c24b6b63b03ac0a4532671a1a9a40a
libxc: allow caller to specify no re-entrancy protection when opening the
interface
Used by language bindings which provide their own re-entrancy which conflicts
with pthreads.
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
diff -r 61797efad6c2 -r 3de336d9c113 tools/libxc/xc_private.c
--- a/tools/libxc/xc_private.c Thu Nov 18 05:46:26 2010 -0500
+++ b/tools/libxc/xc_private.c Thu Nov 18 05:46:26 2010 -0500
@@ -32,6 +32,7 @@ xc_interface *xc_interface_open(xentooll
unsigned open_flags) {
xc_interface xch_buf, *xch = &xch_buf;
+ xch->flags = open_flags;
xch->fd = -1;
xch->dombuild_logger_file = 0;
xc_clear_last_error(xch);
@@ -546,30 +547,37 @@ _xc_init_errbuf(void)
char *_xc_strerror(xc_interface *xch, int errcode)
{
+ if ( xch->flags & XC_OPENFLAG_NON_REENTRANT )
+ {
+ return strerror(errcode);
+ }
+ else
+ {
#define XS_BUFSIZE 32
- char *errbuf;
- static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
- char *strerror_str;
+ char *errbuf;
+ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+ char *strerror_str;
- pthread_once(&errbuf_pkey_once, _xc_init_errbuf);
+ pthread_once(&errbuf_pkey_once, _xc_init_errbuf);
- errbuf = pthread_getspecific(errbuf_pkey);
- if (errbuf == NULL) {
- errbuf = malloc(XS_BUFSIZE);
- pthread_setspecific(errbuf_pkey, errbuf);
+ errbuf = pthread_getspecific(errbuf_pkey);
+ if (errbuf == NULL) {
+ errbuf = malloc(XS_BUFSIZE);
+ pthread_setspecific(errbuf_pkey, errbuf);
+ }
+
+ /*
+ * Thread-unsafe strerror() is protected by a local mutex. We copy the
+ * string to a thread-private buffer before releasing the mutex.
+ */
+ pthread_mutex_lock(&mutex);
+ strerror_str = strerror(errcode);
+ strncpy(errbuf, strerror_str, XS_BUFSIZE);
+ errbuf[XS_BUFSIZE-1] = '\0';
+ pthread_mutex_unlock(&mutex);
+
+ return errbuf;
}
-
- /*
- * Thread-unsafe strerror() is protected by a local mutex. We copy
- * the string to a thread-private buffer before releasing the mutex.
- */
- pthread_mutex_lock(&mutex);
- strerror_str = strerror(errcode);
- strncpy(errbuf, strerror_str, XS_BUFSIZE);
- errbuf[XS_BUFSIZE-1] = '\0';
- pthread_mutex_unlock(&mutex);
-
- return errbuf;
}
void bitmap_64_to_byte(uint8_t *bp, const uint64_t *lp, int nbits)
diff -r 61797efad6c2 -r 3de336d9c113 tools/libxc/xc_private.h
--- a/tools/libxc/xc_private.h Thu Nov 18 05:46:26 2010 -0500
+++ b/tools/libxc/xc_private.h Thu Nov 18 05:46:26 2010 -0500
@@ -67,6 +67,7 @@
struct xc_interface {
int fd;
+ int flags;
xentoollog_logger *error_handler, *error_handler_tofree;
xentoollog_logger *dombuild_logger, *dombuild_logger_tofree;
struct xc_error last_error; /* for xc_get_last_error */
diff -r 61797efad6c2 -r 3de336d9c113 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h Thu Nov 18 05:46:26 2010 -0500
+++ b/tools/libxc/xenctrl.h Thu Nov 18 05:46:26 2010 -0500
@@ -132,8 +132,17 @@ xc_interface *xc_interface_open(xentooll
* if dombuild_logger=NULL, will log to a file
*/
+/*
+ * Note: if XC_OPENFLAG_NON_REENTRANT is passed then libxc must not be
+ * called reentrantly and the calling application is responsible for
+ * providing mutual exclusion surrounding all libxc calls itself.
+ *
+ * In particular xc_{get,clear}_last_error only remain valid for the
+ * duration of the critical section containing the call which failed.
+ */
enum xc_open_flags {
- XC_OPENFLAG_DUMMY = 01, /* do not actually open a xenctrl interface */
+ XC_OPENFLAG_DUMMY = 1<<0, /* do not actually open a xenctrl interface */
+ XC_OPENFLAG_NON_REENTRANT = 1<<1, /* assume library is only every called
from a single thread */
};
/**
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