From 7d0fdfd0a3e5165020e11892079154ef1e1d691f Mon Sep 17 00:00:00 2001 From: Sergio Lopez Date: Fri, 27 Aug 2010 00:24:01 +0200 Subject: make unblocked reads from external objects return a zeroed page. * serverboot/default_pager.c (struct dstruct): Add boolean_t external field. (default_pager_add): Set ds->external to TRUE or FALSE depending whether the object is external. (default_read): Add external parameter. If no_block(block) returns 1, if external is TRUE, zero fill the page and return PAGER_SUCCESS instead of PAGER_ABSENT. (seqnos_memory_object_data_request): Pass ds->external as additional parameter to default_read. --- serverboot/default_pager.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'serverboot') diff --git a/serverboot/default_pager.c b/serverboot/default_pager.c index aa7b0885..3a3f0e4f 100644 --- a/serverboot/default_pager.c +++ b/serverboot/default_pager.c @@ -1668,7 +1668,7 @@ ok: * if it is different from , it must be deallocated after use. */ int -default_read(ds, addr, size, offset, out_addr, deallocate) +default_read(ds, addr, size, offset, out_addr, deallocate, external) register dpager_t ds; vm_offset_t addr; /* pointer to block to fill */ register vm_size_t size; @@ -1676,6 +1676,7 @@ default_read(ds, addr, size, offset, out_addr, deallocate) vm_offset_t *out_addr; /* returns pointer to data */ boolean_t deallocate; + boolean_t external; { register union dp_map block; vm_offset_t raddr; @@ -1692,8 +1693,18 @@ default_read(ds, addr, size, offset, out_addr, deallocate) * Find the block in the paging partition */ block = pager_read_offset(ds, offset); - if ( no_block(block) ) + if ( no_block(block) ) { + if (external) { + /* + * An external object is requesting unswapped data, + * zero fill the page and return. + */ + bzero((char *) addr, vm_page_size); + *out_addr = addr; + return (PAGER_SUCCESS); + } return (PAGER_ABSENT); + } /* * Read it, trying for the entire page. @@ -1844,6 +1855,7 @@ struct dstruct { mach_port_urefs_t request_refs; /* Request port user-refs */ mach_port_t pager_name; /* Name port */ mach_port_urefs_t name_refs; /* Name port user-refs */ + boolean_t external; /* Is an external object? */ unsigned int readers; /* Reads in progress */ unsigned int writers; /* Writes in progress */ @@ -2301,10 +2313,12 @@ void default_pager_add(ds, internal) /* possibly generate an immediate no-senders notification */ sync = 0; pset = default_pager_internal_set; + ds->external = FALSE; } else { /* delay notification till send right is created */ sync = 1; pset = default_pager_external_set; + ds->external = TRUE; } kr = mach_port_request_notification(default_pager_self, pager, @@ -2655,7 +2669,8 @@ ddprintf ("seqnos_memory_object_data_request <%p>: pager_port_unlock: <%p>[s:%d, else rc = default_read(&ds->dpager, dpt->dpt_buffer, vm_page_size, offset, - &addr, protection_required & VM_PROT_WRITE); + &addr, protection_required & VM_PROT_WRITE, + ds->external); switch (rc) { case PAGER_SUCCESS: -- cgit v1.2.3