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Update synchronization annotations for struct vm_page. Add a comment

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explaining how the setting of PG_WRITEABLE is synchronized.
This commit is contained in:
alc 2010-05-11 01:29:18 +00:00
parent c4a8bb5da4
commit bb095a7b97
1 changed files with 8 additions and 5 deletions
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13
sys/vm/vm_page.h
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@ -112,7 +112,7 @@ struct vm_page {
u_short flags; /* see below */
uint8_t order; /* index of the buddy queue */
uint8_t pool;
u_short cow; /* page cow mapping count (Q) */
u_short cow; /* page cow mapping count (P) */
u_int wire_count; /* wired down maps refs (P) */
short hold_count; /* page hold count (P) */
u_short oflags; /* page flags (O) */
@ -122,16 +122,16 @@ struct vm_page {
/* so, on normal X86 kernels, they must be at least 8 bits wide */
#if PAGE_SIZE == 4096
u_char valid; /* map of valid DEV_BSIZE chunks (O) */
u_char dirty; /* map of dirty DEV_BSIZE chunks */
u_char dirty; /* map of dirty DEV_BSIZE chunks (O) */
#elif PAGE_SIZE == 8192
u_short valid; /* map of valid DEV_BSIZE chunks (O) */
u_short dirty; /* map of dirty DEV_BSIZE chunks */
u_short dirty; /* map of dirty DEV_BSIZE chunks (O) */
#elif PAGE_SIZE == 16384
u_int valid; /* map of valid DEV_BSIZE chunks (O) */
u_int dirty; /* map of dirty DEV_BSIZE chunks */
u_int dirty; /* map of dirty DEV_BSIZE chunks (O) */
#elif PAGE_SIZE == 32768
u_long valid; /* map of valid DEV_BSIZE chunks (O) */
u_long dirty; /* map of dirty DEV_BSIZE chunks */
u_long dirty; /* map of dirty DEV_BSIZE chunks (O) */
#endif
};
@ -216,6 +216,9 @@ extern struct vpglocks pa_lock[];
* via the object/vm_page_t because there is no knowledge of their
* pte mappings, nor can they be removed from their objects via
* the object, and such pages are also not on any PQ queue.
*
* PG_WRITEABLE is set exclusively by pmap_enter(). When it does so, either
* the page must be VPO_BUSY or the containing object must be locked.
*/
#define PG_CACHED 0x0001 /* page is cached */
#define PG_FREE 0x0002 /* page is free */