[PATCH v6 4/4] ntdll: Keep pagemap file open after first use of NtQueryVirtualMemory(MemoryWorkingSetExInformation)

[Witold Baryluk]

From: Witold Baryluk

---
 dlls/ntdll/unix/virtual.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/dlls/ntdll/unix/virtual.c b/dlls/ntdll/unix/virtual.c
index 868c226e33f..600b0dafa8f 100644
--- a/dlls/ntdll/unix/virtual.c
+++ b/dlls/ntdll/unix/virtual.c
@@ -199,6 +199,8 @@ static BYTE **pages_vprot;
 static BYTE *pages_vprot;
 #endif

+static int pagemap_fd = -1;
+
 static struct file_view *view_block_start, *view_block_end, *next_free_view;
 static const size_t view_block_size = 0x100000;
 static void *preload_reserve_start;
@@ -4203,7 +4205,6 @@ static NTSTATUS get_working_set_ex( HANDLE process, LPCVOID addr,
                                     MEMORY_WORKING_SET_EX_INFORMATION *info,
                                     SIZE_T len, SIZE_T *res_len )
 {
-    int pagemap_fd;
     MEMORY_WORKING_SET_EX_INFORMATION *p;
     sigset_t sigset;

@@ -4266,14 +4267,16 @@ static NTSTATUS get_working_set_ex( HANDLE process, LPCVOID addr,
             procstat_close( pstat );
     }
 #else
-    pagemap_fd = open( "/proc/self/pagemap", O_RDONLY, 0 );
-    if (pagemap_fd == -1)
+    server_enter_uninterrupted_section( &virtual_mutex, &sigset );
     {
-        static int once;
-        if (!once++) WARN( "unable to open /proc/self/pagemap\n" );
+        static int once = 0;
+        if (once == 0 && pagemap_fd == -1) {
+            once = 1;
+            pagemap_fd = open( "/proc/self/pagemap", O_RDONLY, 0 );
+            if (pagemap_fd == -1) WARN( "unable to open /proc/self/pagemap\n" );
+        }
     }

-    server_enter_uninterrupted_section( &virtual_mutex, &sigset );
     for (p = info; (UINT_PTR)(p + 1) <= (UINT_PTR)info + len; p++)
     {
         BYTE vprot;
@@ -4304,8 +4307,6 @@ static NTSTATUS get_working_set_ex( HANDLE process, LPCVOID addr,
     server_leave_uninterrupted_section( &virtual_mutex, &sigset );
 #endif

-    if (pagemap_fd != -1)
-        close( pagemap_fd );
     if (res_len)
         *res_len = (UINT_PTR)p - (UINT_PTR)info;
     return STATUS_SUCCESS;