To avoid a conflict for the vm_map's lock with vm_fault, release
the read lock around the subyte operations in mincore. After the lock is reacquired, use the map's timestamp to determine if we need to restart the scan.
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=44438
@ -38,7 +38,7 @@
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* from: Utah $Hdr: vm_mmap.c 1.6 91/10/21$
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*
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* @(#)vm_mmap.c 8.4 (Berkeley) 1/12/94
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* $Id: vm_mmap.c,v 1.90 1999/02/19 14:25:36 luoqi Exp $
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* $Id: vm_mmap.c,v 1.91 1999/03/01 20:42:16 alc Exp $
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*/
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/*
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@ -675,6 +675,7 @@ mincore(p, uap)
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register vm_map_entry_t current;
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vm_map_entry_t entry;
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int mincoreinfo;
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unsigned int timestamp;
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/*
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* Make sure that the addresses presented are valid for user
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@ -696,6 +697,8 @@ mincore(p, uap)
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pmap = vmspace_pmap(p->p_vmspace);
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vm_map_lock_read(map);
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RestartScan:
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timestamp = map->timestamp;
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if (!vm_map_lookup_entry(map, addr, &entry))
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entry = entry->next;
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@ -765,6 +768,12 @@ mincore(p, uap)
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}
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}
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/*
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* subyte may page fault. In case it needs to modify
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* the map, we release the lock.
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*/
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vm_map_unlock_read(map);
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/*
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* calculate index into user supplied byte vector
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*/
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@ -777,7 +786,6 @@ mincore(p, uap)
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while((lastvecindex + 1) < vecindex) {
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error = subyte( vec + lastvecindex, 0);
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if (error) {
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vm_map_unlock_read(map);
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return (EFAULT);
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}
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++lastvecindex;
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@ -788,14 +796,28 @@ mincore(p, uap)
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*/
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error = subyte( vec + vecindex, mincoreinfo);
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if (error) {
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vm_map_unlock_read(map);
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return (EFAULT);
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}
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/*
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* If the map has changed, due to the subyte, the previous
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* output may be invalid.
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*/
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vm_map_lock_read(map);
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if (timestamp != map->timestamp)
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goto RestartScan;
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lastvecindex = vecindex;
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addr += PAGE_SIZE;
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}
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}
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/*
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* subyte may page fault. In case it needs to modify
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* the map, we release the lock.
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*/
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vm_map_unlock_read(map);
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/*
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* Zero the last entries in the byte vector.
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*/
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@ -803,13 +825,20 @@ mincore(p, uap)
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while((lastvecindex + 1) < vecindex) {
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error = subyte( vec + lastvecindex, 0);
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if (error) {
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vm_map_unlock_read(map);
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return (EFAULT);
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}
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++lastvecindex;
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}
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/*
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* If the map has changed, due to the subyte, the previous
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* output may be invalid.
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*/
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vm_map_lock_read(map);
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if (timestamp != map->timestamp)
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goto RestartScan;
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vm_map_unlock_read(map);
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return (0);
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}
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