Changeset 629 for trunk/kernel/libk/user_dir.c

Timestamp:

May 17, 2019, 9:27:04 AM (5 years ago)

Author:

alain

Message:

Remove the "giant" rwlock protecting the GPT, and
use the GPT_LOCKED attribute in each PTE to prevent
concurrent modifications of one GPT entry.
The version number has been incremented to 2.1.

File:

• trunk/kernel/libk/user_dir.c (modified) (8 diffs)

trunk/kernel/libk/user_dir.c

@@ -2 +2 @@
  * user_dir.c - kernel DIR related operations implementation.
  * 
- * Authors   Alain   Greiner (2016,2017,2018)
+ * Authors   Alain   Greiner (2016,2017,2018,2019)
  *
  * Copyright (c) UPMC Sorbonne Universites
@@ -91 +91 @@
     pid_t           ref_pid;           // reference process PID
     xptr_t          gpt_xp;            // extended pointer on reference process GPT
-    uint32_t        gpt_attributes;    // attributes for all mapped gpt entries
+    uint32_t        attr;              // attributes for all GPT entries
     uint32_t        dirents_per_page;  // number of dirent descriptors per page
     xptr_t          page_xp;           // extended pointer on page descriptor  
@@ -99 +99 @@
     uint32_t        total_dirents;     // total number of dirents in dirent array
     uint32_t        total_pages;       // total number of pages for dirent array
-    vpn_t           vpn;               // first page in dirent array vseg
+    vpn_t           vpn_base;          // first page in dirent array vseg
+    vpn_t           vpn;               // current page in dirent array vseg
     ppn_t           ppn;               // ppn of currently allocated physical page
     uint32_t        entries;           // number of dirent actually comied in one page
@@ -107 +108 @@
     uint32_t        page_id;           // page index in list of physical pages
     kmem_req_t      req;               // kmem request descriptor
+    ppn_t           fake_ppn;          // unused, but required by hal_gptlock_pte()
+    uint32_t        fake_attr;         // unused, but required by hal_gptlock_pte()
     error_t         error;
 
-    // get cluster, local pointer, and pid of reference user process
+    // get cluster, local pointer, and pid of reference process
     ref_cxy = GET_CXY( ref_xp );
     ref_ptr = GET_PTR( ref_xp );
@@ -256 +259 @@
 "unconsistent vseg size for dirent array" );
 
-    // build extended pointer on reference process GPT, PTE attributes and ppn
+    // build extended pointer on reference process GPT
     gpt_xp         = XPTR( ref_cxy , &ref_ptr->vmm.gpt );
-    gpt_attributes = GPT_MAPPED   |
-                     GPT_SMALL    |
-                     GPT_READABLE |
-                     GPT_CACHABLE |
-                     GPT_USER     ;
+
+    // build PTE attributes
+    attr = GPT_MAPPED   |
+           GPT_SMALL    |
+           GPT_READABLE |
+           GPT_CACHABLE |
+           GPT_USER     ;
 
     // get first vpn from vseg descriptor
-    vpn = hal_remote_l32( XPTR( ref_cxy , &vseg->vpn_base ) );
+    vpn_base = hal_remote_l32( XPTR( ref_cxy , &vseg->vpn_base ) );
 
     // scan the list of allocated physical pages to map
-    // all physical pages in the in the reference process GPT
+    // all physical pages in the reference process GPT
     page_id = 0;
     while( list_is_empty( &root ) == false )
@@ -277 +282 @@
         // compute ppn
         ppn = ppm_page2ppn( XPTR( local_cxy , page ) );
+
+        // compute vpn
+        vpn = vpn_base + page_id;
         
-        error = hal_gpt_set_pte( gpt_xp,
-                                 vpn + page_id,
-                                 gpt_attributes,
-                                 ppn );
+        // lock the PTE (and create PT2 if required)
+        error = hal_gpt_lock_pte( gpt_xp,
+                                  vpn,
+                                  &fake_attr,
+                                  &fake_ppn );
         if( error )
         {
             printk("\n[ERROR] in %s : cannot map vpn %x in GPT\n",
-            __FUNCTION__, (vpn + page_id) );
+            __FUNCTION__, vpn );
 
             // delete the vseg
-            if( ref_cxy == local_cxy) vmm_delete_vseg( ref_pid, vpn<<CONFIG_PPM_PAGE_SHIFT );
-            else rpc_vmm_delete_vseg_client( ref_cxy, ref_pid, vpn<<CONFIG_PPM_PAGE_SHIFT );
+            if( ref_cxy == local_cxy)
+                vmm_delete_vseg( ref_pid, vpn_base << CONFIG_PPM_PAGE_SHIFT );
+            else 
+                rpc_vmm_delete_vseg_client( ref_cxy, ref_pid, vpn_base << CONFIG_PPM_PAGE_SHIFT );
 
             // release the user_dir descriptor
@@ -298 +309 @@
         }
 
+        // set PTE in GPT                          
+        hal_gpt_set_pte( gpt_xp,
+                         vpn,
+                         attr,
+                         ppn );
+
 #if DEBUG_USER_DIR 
 if( cycle > DEBUG_USER_DIR )
@@ -317 +334 @@
     dir->current = 0;
     dir->entries = total_dirents;
-    dir->ident   = (intptr_t)(vpn << CONFIG_PPM_PAGE_SHIFT);
+    dir->ident   = (intptr_t)(vpn_base << CONFIG_PPM_PAGE_SHIFT);
 
     // build extended pointers on root and lock of user_dir xlist in ref process