mtd: mtdram: properly handle the phys argument in the point method (877b58eb) · Commits · 戴 / test

When the phys pointer is non null, the point method is expected to return the physical address for the pointed area. In the case of the mtdram driver we have to retrieve the physical address for the corresponding vmalloc area. However, there is no guarantee that the vmalloc area is made of physically contiguous pages. In that case we simply limit retlen to the actually contiguous pages. Signed-off-by:

Nicolas Pitre <nico@linaro.org> Reviewed-by:

Richard Weinberger <richard@nod.at> Acked-by:

Boris Brezillon <boris.brezillon@free-electrons.com> Signed-off-by:

Richard Weinberger <richard@nod.at>

drivers/mtd/devices/mtdram.c

+22 −0

Original line number	Diff line number	Diff line
		@@ -13,6 +13,7 @@
		#include <linux/slab.h>
		#include <linux/ioport.h>
		#include <linux/vmalloc.h>
		#include <linux/mm.h>
		#include <linux/init.h>
		#include <linux/mtd/mtd.h>
		#include <linux/mtd/mtdram.h>
		@@ -69,6 +70,27 @@ static int ram_point(struct mtd_info *mtd, loff_t from, size_t len,
		{
		*virt = mtd->priv + from;
		*retlen = len;

		if (phys) {
		/* limit retlen to the number of contiguous physical pages */
		unsigned long page_ofs = offset_in_page(*virt);
		void addr = virt - page_ofs;
		unsigned long pfn1, pfn0 = vmalloc_to_pfn(addr);

		*phys = __pfn_to_phys(pfn0) + page_ofs;
		len += page_ofs;
		while (len > PAGE_SIZE) {
		len -= PAGE_SIZE;
		addr += PAGE_SIZE;
		pfn0++;
		pfn1 = vmalloc_to_pfn(addr);
		if (pfn1 != pfn0) {
		retlen = addr - virt;
		break;
		}
		}
		}

		return 0;
		}

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