6.8-stable review patch. If anyone has any objections, please let me know.
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From: Miquel Raynal miquel.raynal@bootlin.com
[ Upstream commit c7ee7c8d4b60fe46d4861b1200bc1c7ab657960a ]
We need to avoid the first page if we don't read it entirely. We need to avoid the last page if we don't read it entirely. While rather simple, this logic has been failed in the previous fix. This time I wrote about 30 unit tests locally to check each possible condition, hopefully I covered them all.
Reported-by: Christophe Kerello christophe.kerello@foss.st.com Closes: https://lore.kernel.org/linux-mtd/20240221175327.42f7076d@xps-13/T/#m399bacb... Suggested-by: Christophe Kerello christophe.kerello@foss.st.com Fixes: 828f6df1bcba ("mtd: rawnand: Clarify conditions to enable continuous reads") Cc: stable@vger.kernel.org Signed-off-by: Miquel Raynal miquel.raynal@bootlin.com Tested-by: Christophe Kerello christophe.kerello@foss.st.com Link: https://lore.kernel.org/linux-mtd/20240223115545.354541-2-miquel.raynal@boot... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mtd/nand/raw/nand_base.c | 34 +++++++++++++++++++------------- 1 file changed, 20 insertions(+), 14 deletions(-)
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 3b3ce2926f5d1..bcfd99a1699fd 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -3466,30 +3466,36 @@ static void rawnand_enable_cont_reads(struct nand_chip *chip, unsigned int page, u32 readlen, int col) { struct mtd_info *mtd = nand_to_mtd(chip); - unsigned int end_page, end_col; + unsigned int first_page, last_page;
chip->cont_read.ongoing = false;
if (!chip->controller->supported_op.cont_read) return;
- end_page = DIV_ROUND_UP(col + readlen, mtd->writesize); - end_col = (col + readlen) % mtd->writesize; + /* + * Don't bother making any calculations if the length is too small. + * Side effect: avoids possible integer underflows below. + */ + if (readlen < (2 * mtd->writesize)) + return;
+ /* Derive the page where continuous read should start (the first full page read) */ + first_page = page; if (col) - page++; - - if (end_col && end_page) - end_page--; + first_page++;
- if (page + 1 > end_page) - return; - - chip->cont_read.first_page = page; - chip->cont_read.last_page = end_page; - chip->cont_read.ongoing = true; + /* Derive the page where continuous read should stop (the last full page read) */ + last_page = page + ((col + readlen) / mtd->writesize) - 1;
- rawnand_cap_cont_reads(chip); + /* Configure and enable continuous read when suitable */ + if (first_page < last_page) { + chip->cont_read.first_page = first_page; + chip->cont_read.last_page = last_page; + chip->cont_read.ongoing = true; + /* May reset the ongoing flag */ + rawnand_cap_cont_reads(chip); + } }
static void rawnand_cont_read_skip_first_page(struct nand_chip *chip, unsigned int page)