Protect the creation of the device pager with the dev_pager_mtx. Lookup
of device pager in the pagers list by handle is now synchronized with its removal from the list, and dev_pager_mtx is put before vm object lock in lock order. Dispose the dev_pager_sx lock, since dev_pager_mtx now covers the same block. Noted by: kensmith Reviewed by: alc Approved by: re (kensmith)
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parent
5a5ee8cb1e
commit
deea654ebf
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=171779
@ -64,8 +64,6 @@ static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
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/* list of device pager objects */
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static struct pagerlst dev_pager_object_list;
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/* protect against object creation */
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static struct sx dev_pager_sx;
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/* protect list manipulation */
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static struct mtx dev_pager_mtx;
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@ -89,7 +87,6 @@ static void
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dev_pager_init()
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{
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TAILQ_INIT(&dev_pager_object_list);
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sx_init(&dev_pager_sx, "dev_pager create");
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mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
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fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
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NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
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@ -103,7 +100,7 @@ static vm_object_t
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dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff)
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{
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struct cdev *dev;
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vm_object_t object;
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vm_object_t object, object1;
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vm_pindex_t pindex;
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unsigned int npages;
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vm_paddr_t paddr;
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@ -143,29 +140,42 @@ dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t fo
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/*
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* Lock to prevent object creation race condition.
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*/
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sx_xlock(&dev_pager_sx);
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mtx_lock(&dev_pager_mtx);
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/*
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* Look up pager, creating as necessary.
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*/
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object1 = NULL;
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object = vm_pager_object_lookup(&dev_pager_object_list, handle);
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if (object == NULL) {
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/*
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* Allocate object and associate it with the pager.
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*/
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object = vm_object_allocate(OBJT_DEVICE, pindex);
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object->handle = handle;
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TAILQ_INIT(&object->un_pager.devp.devp_pglist);
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mtx_lock(&dev_pager_mtx);
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TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
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mtx_unlock(&dev_pager_mtx);
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object1 = vm_object_allocate(OBJT_DEVICE, pindex);
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mtx_lock(&dev_pager_mtx);
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object = vm_pager_object_lookup(&dev_pager_object_list, handle);
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if (object != NULL) {
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/*
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* We raced with other thread while allocating object.
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*/
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if (pindex > object->size)
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object->size = pindex;
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} else {
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object = object1;
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object1 = NULL;
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object->handle = handle;
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TAILQ_INIT(&object->un_pager.devp.devp_pglist);
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TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
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pager_object_list);
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}
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} else {
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if (pindex > object->size)
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object->size = pindex;
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}
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sx_xunlock(&dev_pager_sx);
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mtx_unlock(&dev_pager_mtx);
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dev_relthread(dev);
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vm_object_deallocate(object1);
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return (object);
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}
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@ -175,9 +185,11 @@ dev_pager_dealloc(object)
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{
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vm_page_t m;
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VM_OBJECT_UNLOCK(object);
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mtx_lock(&dev_pager_mtx);
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TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
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mtx_unlock(&dev_pager_mtx);
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VM_OBJECT_LOCK(object);
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/*
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* Free up our fake pages.
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*/
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