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[Xen-devel] [PATCH] libxc: free thread specific hypercall buffer on xc_i

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] [PATCH] libxc: free thread specific hypercall buffer on xc_interface_close
From: Ian Campbell <ian.campbell@xxxxxxxxxx>
Date: Wed, 18 Aug 2010 16:01:07 +0100
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
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# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1282143629 -3600
# Node ID b1f4b4be1f94c0007794f86abd019f5c2629c59b
# Parent  ddbd38da07397dca4760fb687551c3f6f9134700
libxc: free thread specific hypercall buffer on xc_interface_close

The per-thread hypercall buffer is usually cleaned up on pthread_exit
by the destructor passed to pthread_key_create. However if the calling
application is not threaded then the destructor is never called.

This frees the data for the current thread only but that is OK since
any other threads will be cleaned up by the destructor.

Changed since v1:
 * Ensure hcall_buf_pkey is initialised before use. Thanks to
   Christoph Egger for his help diagnosing this issue on NetBSD.
 * Remove redundant if (hcall_buf) from xc_clean_hcall_buf since
   _xc_clean_hcall_buf includes the same check.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r ddbd38da0739 -r b1f4b4be1f94 tools/libxc/xc_private.c
--- a/tools/libxc/xc_private.c  Wed Aug 18 13:14:57 2010 +0100
+++ b/tools/libxc/xc_private.c  Wed Aug 18 16:00:29 2010 +0100
@@ -57,6 +57,8 @@ xc_interface *xc_interface_open(xentooll
     return 0;
+static void xc_clean_hcall_buf(void);
 int xc_interface_close(xc_interface *xch)
     int rc = 0;
@@ -68,6 +70,9 @@ int xc_interface_close(xc_interface *xch
         rc = xc_interface_close_core(xch, xch->fd);
         if (rc) PERROR("Could not close hypervisor interface");
+    xc_clean_hcall_buf();
     return rc;
@@ -180,6 +185,8 @@ int hcall_buf_prep(void **addr, size_t l
 int hcall_buf_prep(void **addr, size_t len) { return 0; }
 void hcall_buf_release(void **addr, size_t len) { }
+static void xc_clean_hcall_buf(void) { }
 #else /* !__sun__ */
 int lock_pages(void *addr, size_t len)
@@ -228,6 +235,13 @@ static void _xc_init_hcall_buf(void)
 static void _xc_init_hcall_buf(void)
     pthread_key_create(&hcall_buf_pkey, _xc_clean_hcall_buf);
+static void xc_clean_hcall_buf(void)
+    pthread_once(&hcall_buf_pkey_once, _xc_init_hcall_buf);
+    _xc_clean_hcall_buf(pthread_getspecific(hcall_buf_pkey));
 int hcall_buf_prep(void **addr, size_t len)

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