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Guard against an integer underflow that could cause busdma to eat up all

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available RAM.  This also results in the global bounce page limit being
applied to zones instead of globally.

Submitted by: Petr Lampa (in part)
This commit is contained in:
Scott Long 2005-03-12 07:01:53 +00:00
parent d2014b3079
commit ba74ba674f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=143449
1 changed files with 9 additions and 3 deletions
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12
sys/i386/i386/busdma_machdep.c
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@ -382,12 +382,14 @@ bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
/* Must bounce */
struct bounce_zone *bz;
int maxpages;
if (dmat->bounce_zone == NULL) {
if ((error = alloc_bounce_zone(dmat)) != 0)
return (error);
}
bz = dmat->bounce_zone;
*mapp = (bus_dmamap_t)malloc(sizeof(**mapp), M_DEVBUF,
M_NOWAIT | M_ZERO);
@ -404,13 +406,17 @@ bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
* Attempt to add pages to our pool on a per-instance
* basis up to a sane limit.
*/
maxpages = MIN(MAX_BPAGES, Maxmem - atop(dmat->lowaddr));
if (dmat->alignment > 1)
maxpages = MAX_BPAGES;
else
maxpages = MIN(MAX_BPAGES, Maxmem -atop(dmat->lowaddr));
if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
|| (dmat->map_count > 0 && total_bpages < maxpages)) {
|| (dmat->map_count > 0 && bz->total_bpages < maxpages)) {
int pages;
pages = MAX(atop(dmat->maxsize), 1);
pages = MIN(maxpages - total_bpages, pages);
pages = MIN(maxpages - bz->total_bpages, pages);
pages = MAX(pages, 1);
if (alloc_bounce_pages(dmat, pages) < pages)
error = ENOMEM;