Commit aff12700 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Jon Mason
Browse files

ntb: reduce stack usage in idt_scan_mws 



idt_scan_mws() puts a large fixed-size array on the stack and copies
it into a smaller dynamically allocated array at the end. On 32-bit
targets, the fixed size can easily exceed the warning limit for
possible stack overflow:

drivers/ntb/hw/idt/ntb_hw_idt.c:1041:27: error: stack frame size (1032) exceeds limit (1024) in 'idt_scan_mws' [-Werror,-Wframe-larger-than]

Change it to instead just always use dynamic allocation for the
array from the start. It's too big for the stack, but not actually
all that much for a permanent allocation.

Reported-by: default avatarkernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/all/202205111109.PiKTruEj-lkp@intel.com/


Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarDave Jiang <dave.jiang@intel.com>
Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Signed-off-by: default avatarJon Mason <jdmason@kudzu.us>
parent fd5625fc

drivers/ntb/hw/idt/ntb_hw_idt.c

+7 −11
Original line number Diff line number Diff line
@@ -1041,7 +1041,7 @@ static inline char *idt_get_mw_name(enum idt_mw_type mw_type) 
static struct idt_mw_cfg *idt_scan_mws(struct idt_ntb_dev *ndev, int port,

				       unsigned char *mw_cnt)

{

	struct idt_mw_cfg mws[IDT_MAX_NR_MWS], *ret_mws;

	struct idt_mw_cfg *mws;

	const struct idt_ntb_bar *bars;

	enum idt_mw_type mw_type;

	unsigned char widx, bidx, en_cnt;
@@ -1049,6 +1049,11 @@ static struct idt_mw_cfg *idt_scan_mws(struct idt_ntb_dev *ndev, int port, 
	int aprt_size;

	u32 data;



	mws = devm_kcalloc(&ndev->ntb.pdev->dev, IDT_MAX_NR_MWS,

			   sizeof(*mws), GFP_KERNEL);

	if (!mws)

		return ERR_PTR(-ENOMEM);



	/* Retrieve the array of the BARs registers */

	bars = portdata_tbl[port].bars;
@@ -1103,16 +1108,7 @@ static struct idt_mw_cfg *idt_scan_mws(struct idt_ntb_dev *ndev, int port, 
		}

	}



	/* Allocate memory for memory window descriptors */

	ret_mws = devm_kcalloc(&ndev->ntb.pdev->dev, *mw_cnt, sizeof(*ret_mws),

			       GFP_KERNEL);

	if (!ret_mws)

		return ERR_PTR(-ENOMEM);



	/* Copy the info of detected memory windows */

	memcpy(ret_mws, mws, (*mw_cnt)*sizeof(*ret_mws));



	return ret_mws;

	return mws;

}



/*