Date: Fri, 12 Oct 2012 03:09:59 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r241478 - stable/9/sys/vm Message-ID: <201210120309.q9C39xSJ030816@svn.freebsd.org>
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Author: alc Date: Fri Oct 12 03:09:59 2012 New Revision: 241478 URL: http://svn.freebsd.org/changeset/base/241478 Log: MFC r241155 Update some of the comments. In particular, use "sleep" in preference to "block" where appropriate. Eliminate some unnecessary casts. Make a few whitespace changes for consistency. Modified: stable/9/sys/vm/vm_page.c Modified: stable/9/sys/vm/vm_page.c ============================================================================== --- stable/9/sys/vm/vm_page.c Fri Oct 12 02:12:53 2012 (r241477) +++ stable/9/sys/vm/vm_page.c Fri Oct 12 03:09:59 2012 (r241478) @@ -904,11 +904,10 @@ vm_page_splay(vm_pindex_t pindex, vm_pag * * The pagetables are not updated but will presumably fault the page * in if necessary, or if a kernel page the caller will at some point - * enter the page into the kernel's pmap. We are not allowed to block + * enter the page into the kernel's pmap. We are not allowed to sleep * here so we *can't* do this anyway. * - * The object and page must be locked. - * This routine may not block. + * The object must be locked. */ void vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex) @@ -952,14 +951,15 @@ vm_page_insert(vm_page_t m, vm_object_t object->root = m; /* - * show that the object has one more resident page. + * Show that the object has one more resident page. */ object->resident_page_count++; + /* * Hold the vnode until the last page is released. */ if (object->resident_page_count == 1 && object->type == OBJT_VNODE) - vhold((struct vnode *)object->handle); + vhold(object->handle); /* * Since we are inserting a new and possibly dirty page, @@ -971,15 +971,14 @@ vm_page_insert(vm_page_t m, vm_object_t /* * vm_page_remove: - * NOTE: used by device pager as well -wfj * * Removes the given mem entry from the object/offset-page * table and the object page list, but do not invalidate/terminate * the backing store. * - * The object and page must be locked. * The underlying pmap entry (if any) is NOT removed here. - * This routine may not block. + * + * The object must be locked. The page must be locked if it is managed. */ void vm_page_remove(vm_page_t m) @@ -1042,11 +1041,12 @@ vm_page_remove(vm_page_t m) * And show that the object has one fewer resident page. */ object->resident_page_count--; + /* * The vnode may now be recycled. */ if (object->resident_page_count == 0 && object->type == OBJT_VNODE) - vdrop((struct vnode *)object->handle); + vdrop(object->handle); m->object = NULL; } @@ -1058,8 +1058,6 @@ vm_page_remove(vm_page_t m) * pair specified; if none is found, NULL is returned. * * The object must be locked. - * This routine may not block. - * This is a critical path routine */ vm_page_t vm_page_lookup(vm_object_t object, vm_pindex_t pindex) @@ -1082,7 +1080,6 @@ vm_page_lookup(vm_object_t object, vm_pi * greater than or equal to the parameter pindex, or NULL. * * The object must be locked. - * The routine may not block. */ vm_page_t vm_page_find_least(vm_object_t object, vm_pindex_t pindex) @@ -1142,9 +1139,6 @@ vm_page_prev(vm_page_t m) * Move the given memory entry from its * current object to the specified target object/offset. * - * The object must be locked. - * This routine may not block. - * * Note: swap associated with the page must be invalidated by the move. We * have to do this for several reasons: (1) we aren't freeing the * page, (2) we are dirtying the page, (3) the VM system is probably @@ -1156,6 +1150,8 @@ vm_page_prev(vm_page_t m) * swap. If the page is on the cache, we have to deactivate it * or vm_page_dirty() will panic. Dirty pages are not allowed * on the cache. + * + * The objects must be locked. The page must be locked if it is managed. */ void vm_page_rename(vm_page_t m, vm_object_t new_object, vm_pindex_t new_pindex) @@ -1675,7 +1671,7 @@ vm_page_alloc_freelist(int flind, int re /* * vm_wait: (also see VM_WAIT macro) * - * Block until free pages are available for allocation + * Sleep until free pages are available for allocation. * - Called in various places before memory allocations. */ void @@ -1700,7 +1696,7 @@ vm_wait(void) /* * vm_waitpfault: (also see VM_WAITPFAULT macro) * - * Block until free pages are available for allocation + * Sleep until free pages are available for allocation. * - Called only in vm_fault so that processes page faulting * can be easily tracked. * - Sleeps at a lower priority than vm_wait() so that vm_wait()ing @@ -1767,7 +1763,6 @@ vm_page_queue_remove(int queue, vm_page_ * Remove a page from its queue. * * The given page must be locked. - * This routine may not block. */ void vm_pageq_remove(vm_page_t m) @@ -1809,7 +1804,6 @@ vm_page_enqueue(int queue, vm_page_t m) * mess with it. * * The page must be locked. - * This routine may not block. */ void vm_page_activate(vm_page_t m) @@ -1844,7 +1838,6 @@ vm_page_activate(vm_page_t m) * queues. * * The page queues must be locked. - * This routine may not block. */ static inline void vm_page_free_wakeup(void) @@ -1877,10 +1870,8 @@ vm_page_free_wakeup(void) * Returns the given page to the free list, * disassociating it with any VM object. * - * Object and page must be locked prior to entry. - * This routine may not block. + * The object must be locked. The page must be locked if it is managed. */ - void vm_page_free_toq(vm_page_t m) { @@ -1898,7 +1889,7 @@ vm_page_free_toq(vm_page_t m) panic("vm_page_free: freeing busy page %p", m); /* - * unqueue, then remove page. Note that we cannot destroy + * Unqueue, then remove page. Note that we cannot destroy * the page here because we do not want to call the pager's * callback routine until after we've put the page on the * appropriate free queue. @@ -1964,7 +1955,6 @@ vm_page_free_toq(vm_page_t m) * If the page is fictitious, then its wire count must remain one. * * The page must be locked. - * This routine may not block. */ void vm_page_wire(vm_page_t m) @@ -2053,7 +2043,7 @@ vm_page_unwire(vm_page_t m, int activate * to 1 if we want this page to be 'as if it were placed in the cache', * except without unmapping it from the process address space. * - * This routine may not block. + * The page must be locked. */ static inline void _vm_page_deactivate(vm_page_t m, int athead) @@ -2145,7 +2135,7 @@ vm_page_try_to_free(vm_page_t m) * * Put the specified page onto the page cache queue (if appropriate). * - * This routine may not block. + * The object and page must be locked. */ void vm_page_cache(vm_page_t m) @@ -2302,6 +2292,8 @@ vm_page_cache(vm_page_t m) * system to balance the queues, potentially recovering other unrelated * space from active. The idea is to not force this to happen too * often. + * + * The object and page must be locked. */ void vm_page_dontneed(vm_page_t m) @@ -2365,7 +2357,10 @@ vm_page_dontneed(vm_page_t m) * The caller must always specify the VM_ALLOC_RETRY flag. This is intended * to facilitate its eventual removal. * - * This routine may block. + * This routine may sleep. + * + * The object must be locked on entry. The lock will, however, be released + * and reacquired if the routine sleeps. */ vm_page_t vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags) @@ -2413,8 +2408,7 @@ retrylookup: } /* - * Mapping function for valid bits or for dirty bits in - * a page. May not block. + * Mapping function for valid or dirty bits in a page. * * Inputs are required to range within a page. */ @@ -2553,8 +2547,6 @@ vm_page_clear_dirty_mask(vm_page_t m, vm * of any partial chunks touched by the range. The invalid portion of * such chunks will be zero'd. * - * This routine may not block. - * * (base + size) must be less then or equal to PAGE_SIZE. */ void @@ -2647,8 +2639,6 @@ vm_page_clear_dirty(vm_page_t m, int bas * * Invalidates DEV_BSIZE'd chunks within a page. Both the * valid and dirty bits for the effected areas are cleared. - * - * May not block. */ void vm_page_set_invalid(vm_page_t m, int base, int size) @@ -2717,8 +2707,6 @@ vm_page_zero_invalid(vm_page_t m, boolea * Is (partial) page valid? Note that the case where size == 0 * will return FALSE in the degenerate case where the page is * entirely invalid, and TRUE otherwise. - * - * May not block. */ int vm_page_is_valid(vm_page_t m, int base, int size) @@ -2734,7 +2722,7 @@ vm_page_is_valid(vm_page_t m, int base, } /* - * update dirty bits from pmap/mmu. May not block. + * Set the page's dirty bits if the page is modified. */ void vm_page_test_dirty(vm_page_t m)
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