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Date: Sat, 21 Apr 2018 10:17:33 +0200
From: Boris Brezillon <boris.brezillon@...tlin.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>, Kees Cook <keescook@...omium.org>,
Segher Boessenkool <segher@...nel.crashing.org>, Kernel Hardening
<kernel-hardening@...ts.openwall.com>, Andrew Morton
<akpm@...uxfoundation.org>, Boris Brezillon
<boris.brezillon@...e-electrons.com>, Richard Weinberger <richard@....at>,
David Woodhouse <dwmw2@...radead.org>, Alasdair Kergon <agk@...hat.com>,
Mike Snitzer <snitzer@...hat.com>, Anton Vorontsov <anton@...msg.org>,
Colin Cross <ccross@...roid.com>, Tony Luck <tony.luck@...el.com>
Subject: Re: [patch V2 6/8] mtd/diskonchip: Allocate rs control per instance
On Thu, 19 Apr 2018 12:04:47 +0200
Thomas Gleixner <tglx@...utronix.de> wrote:
> From: Thomas Gleixner <tglx@...utronix.de>
>
> The reed solomon library is moving the on stack decoder buffers into the rs
> control structure. That would break the DoC driver because multiple
> instances share the same control structure and can operate in parallel. At
> least in theory....
>
> Instantiate a rs control instance per DoC device to avoid that. The per
> instance buffer is fine as the operation on a single DoC instance is
> serialized by the MTD/NAND core.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Boris Brezillon <boris.brezillon@...e-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@...tlin.com>
If you happen to send a new version, can you change the subject prefix
to "mtd: rawnand: diskonchip: " (instead of "mtd/diskonchip: ")?
> Cc: Tony Luck <tony.luck@...el.com>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Segher Boessenkool <segher@...nel.crashing.org>
> Cc: Kernel Hardening <kernel-hardening@...ts.openwall.com>
> Cc: Richard Weinberger <richard@....at>
> Cc: Mike Snitzer <snitzer@...hat.com>
> Cc: Anton Vorontsov <anton@...msg.org>
> Cc: Colin Cross <ccross@...roid.com>
> Cc: Andrew Morton <akpm@...uxfoundation.org>
> Cc: David Woodhouse <dwmw2@...radead.org>
> Cc: Alasdair Kergon <agk@...hat.com>
>
> ---
> drivers/mtd/nand/raw/diskonchip.c | 60 +++++++++++++++++---------------------
> 1 file changed, 27 insertions(+), 33 deletions(-)
>
> --- a/drivers/mtd/nand/raw/diskonchip.c
> +++ b/drivers/mtd/nand/raw/diskonchip.c
> @@ -66,6 +66,7 @@ struct doc_priv {
> int curchip;
> int mh0_page;
> int mh1_page;
> + struct rs_control *rs_decoder;
> struct mtd_info *nextdoc;
>
> /* Handle the last stage of initialization (BBT scan, partitioning) */
> @@ -123,9 +124,6 @@ MODULE_PARM_DESC(doc_config_location, "P
> /* Number of symbols */
> #define NN 1023
>
> -/* the Reed Solomon control structure */
> -static struct rs_control *rs_decoder;
> -
> /*
> * The HW decoder in the DoC ASIC's provides us a error syndrome,
> * which we must convert to a standard syndrome usable by the generic
> @@ -931,7 +929,7 @@ static int doc200x_correct_data(struct m
> calc_ecc[i] = ReadDOC_(docptr, DoC_ECCSyndrome0 + i);
> }
>
> - ret = doc_ecc_decode(rs_decoder, dat, calc_ecc);
> + ret = doc_ecc_decode(doc->rs_decoder, dat, calc_ecc);
> if (ret > 0)
> pr_err("doc200x_correct_data corrected %d errors\n",
> ret);
> @@ -1422,10 +1420,10 @@ static inline int __init doc2001plus_ini
>
> static int __init doc_probe(unsigned long physadr)
> {
> + struct nand_chip *nand = NULL;
> + struct doc_priv *doc = NULL;
> unsigned char ChipID;
> struct mtd_info *mtd;
> - struct nand_chip *nand;
> - struct doc_priv *doc;
> void __iomem *virtadr;
> unsigned char save_control;
> unsigned char tmp, tmpb, tmpc;
> @@ -1562,8 +1560,25 @@ static int __init doc_probe(unsigned lon
> goto fail;
> }
>
> +
> + /*
> + * Allocate a RS codec instance
> + *
> + * Symbolsize is 10 (bits)
> + * Primitve polynomial is x^10+x^3+1
> + * First consecutive root is 510
> + * Primitve element to generate roots = 1
> + * Generator polinomial degree = 4
> + */
> + doc = (struct doc_priv *) (nand + 1);
> + doc->rs_decoder = init_rs(10, 0x409, FCR, 1, NROOTS);
> + if (!doc->rs_decoder) {
> + pr_err("DiskOnChip: Could not create a RS codec\n");
> + ret = -ENOMEM;
> + goto fail;
> + }
> +
> mtd = nand_to_mtd(nand);
> - doc = (struct doc_priv *) (nand + 1);
> nand->bbt_td = (struct nand_bbt_descr *) (doc + 1);
> nand->bbt_md = nand->bbt_td + 1;
>
> @@ -1613,7 +1628,6 @@ static int __init doc_probe(unsigned lon
> haven't yet added it. This is handled without incident by
> mtd_device_unregister, as far as I can tell. */
> nand_release(mtd);
> - kfree(nand);
> goto fail;
> }
>
> @@ -1626,6 +1640,9 @@ static int __init doc_probe(unsigned lon
> actually a DiskOnChip. */
> WriteDOC(save_control, virtadr, DOCControl);
> fail:
> + if (doc)
> + free_rs(doc->rs_decoder);
> + kfree(nand);
> iounmap(virtadr);
>
> error_ioremap:
> @@ -1648,6 +1665,7 @@ static void release_nanddoc(void)
> nand_release(mtd);
> iounmap(doc->virtadr);
> release_mem_region(doc->physadr, DOC_IOREMAP_LEN);
> + free_rs(doc->rs_decoder);
> kfree(nand);
> }
> }
> @@ -1656,27 +1674,12 @@ static int __init init_nanddoc(void)
> {
> int i, ret = 0;
>
> - /* We could create the decoder on demand, if memory is a concern.
> - * This way we have it handy, if an error happens
> - *
> - * Symbolsize is 10 (bits)
> - * Primitve polynomial is x^10+x^3+1
> - * first consecutive root is 510
> - * primitve element to generate roots = 1
> - * generator polinomial degree = 4
> - */
> - rs_decoder = init_rs(10, 0x409, FCR, 1, NROOTS);
> - if (!rs_decoder) {
> - pr_err("DiskOnChip: Could not create a RS decoder\n");
> - return -ENOMEM;
> - }
> -
> if (doc_config_location) {
> pr_info("Using configured DiskOnChip probe address 0x%lx\n",
> doc_config_location);
> ret = doc_probe(doc_config_location);
> if (ret < 0)
> - goto outerr;
> + return ret;
> } else {
> for (i = 0; (doc_locations[i] != 0xffffffff); i++) {
> doc_probe(doc_locations[i]);
> @@ -1687,11 +1690,7 @@ static int __init init_nanddoc(void)
> if (!doclist) {
> pr_info("No valid DiskOnChip devices found\n");
> ret = -ENODEV;
> - goto outerr;
> }
> - return 0;
> - outerr:
> - free_rs(rs_decoder);
> return ret;
> }
>
> @@ -1699,11 +1698,6 @@ static void __exit cleanup_nanddoc(void)
> {
> /* Cleanup the nand/DoC resources */
> release_nanddoc();
> -
> - /* Free the reed solomon resources */
> - if (rs_decoder) {
> - free_rs(rs_decoder);
> - }
> }
>
> module_init(init_nanddoc);
>
>
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