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    Subject[patch V3 01/10] rslib: Add GFP aware init function
    The rslib usage in dm/verity_fec is broken because init_rs() can nest in
    GFP_NOIO mempool allocations as init_rs() is invoked from the mempool alloc
    callback.

    Provide a variant which takes gfp_t flags as argument.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Mike Snitzer <snitzer@redhat.com>
    Cc: Alasdair Kergon <agk@redhat.com>
    Cc: Neil Brown <neilb@suse.com>
    ---
    include/linux/rslib.h | 26 +++++++++++++++++++++++---
    lib/reed_solomon/reed_solomon.c | 36 ++++++++++++++++++++----------------
    2 files changed, 43 insertions(+), 19 deletions(-)

    --- a/include/linux/rslib.h
    +++ b/include/linux/rslib.h
    @@ -77,10 +77,30 @@ int decode_rs16(struct rs_control *rs, u
    #endif

    /* Create or get a matching rs control structure */
    -struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
    - int nroots);
    +struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
    + int nroots, gfp_t gfp);
    +
    +/**
    + * init_rs - Create a RS control struct and initialize it
    + * @symsize: the symbol size (number of bits)
    + * @gfpoly: the extended Galois field generator polynomial coefficients,
    + * with the 0th coefficient in the low order bit. The polynomial
    + * must be primitive;
    + * @fcr: the first consecutive root of the rs code generator polynomial
    + * in index form
    + * @prim: primitive element to generate polynomial roots
    + * @nroots: RS code generator polynomial degree (number of roots)
    + *
    + * Allocations use GFP_KERNEL.
    + */
    +static inline struct rs_control *init_rs(int symsize, int gfpoly, int fcr,
    + int prim, int nroots)
    +{
    + return init_rs_gfp(symsize, gfpoly, fcr, prim, nroots, GFP_KERNEL);
    +}
    +
    struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int),
    - int fcr, int prim, int nroots);
    + int fcr, int prim, int nroots);

    /* Release a rs control structure */
    void free_rs(struct rs_control *rs);
    --- a/lib/reed_solomon/reed_solomon.c
    +++ b/lib/reed_solomon/reed_solomon.c
    @@ -59,19 +59,20 @@ static DEFINE_MUTEX(rslistlock);
    * @fcr: first root of RS code generator polynomial, index form
    * @prim: primitive element to generate polynomial roots
    * @nroots: RS code generator polynomial degree (number of roots)
    + * @gfp: GFP_ flags for allocations
    *
    * Allocate a control structure and the polynom arrays for faster
    * en/decoding. Fill the arrays according to the given parameters.
    */
    static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
    - int fcr, int prim, int nroots)
    + int fcr, int prim, int nroots, gfp_t gfp)
    {
    struct rs_control *rs;
    int i, j, sr, root, iprim;

    /* Allocate the control structure */
    - rs = kmalloc(sizeof (struct rs_control), GFP_KERNEL);
    - if (rs == NULL)
    + rs = kmalloc(sizeof(*rs), gfp);
    + if (!rs)
    return NULL;

    INIT_LIST_HEAD(&rs->list);
    @@ -85,15 +86,15 @@ static struct rs_control *rs_init(int sy
    rs->gffunc = gffunc;

    /* Allocate the arrays */
    - rs->alpha_to = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
    + rs->alpha_to = kmalloc(sizeof(uint16_t) * (rs->nn + 1), gfp);
    if (rs->alpha_to == NULL)
    goto errrs;

    - rs->index_of = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
    + rs->index_of = kmalloc(sizeof(uint16_t) * (rs->nn + 1), gfp);
    if (rs->index_of == NULL)
    goto erralp;

    - rs->genpoly = kmalloc(sizeof(uint16_t) * (rs->nroots + 1), GFP_KERNEL);
    + rs->genpoly = kmalloc(sizeof(uint16_t) * (rs->nroots + 1), gfp);
    if(rs->genpoly == NULL)
    goto erridx;

    @@ -195,13 +196,14 @@ void free_rs(struct rs_control *rs)
    * in index form
    * @prim: primitive element to generate polynomial roots
    * @nroots: RS code generator polynomial degree (number of roots)
    + * @gfp: GFP_ flags for allocations
    */
    static struct rs_control *init_rs_internal(int symsize, int gfpoly,
    - int (*gffunc)(int), int fcr,
    - int prim, int nroots)
    + int (*gffunc)(int), int fcr,
    + int prim, int nroots, gfp_t gfp)
    {
    - struct list_head *tmp;
    - struct rs_control *rs;
    + struct list_head *tmp;
    + struct rs_control *rs;

    /* Sanity checks */
    if (symsize < 1)
    @@ -236,7 +238,7 @@ static struct rs_control *init_rs_intern
    }

    /* Create a new one */
    - rs = rs_init(symsize, gfpoly, gffunc, fcr, prim, nroots);
    + rs = rs_init(symsize, gfpoly, gffunc, fcr, prim, nroots, gfp);
    if (rs) {
    rs->users = 1;
    list_add(&rs->list, &rslist);
    @@ -247,7 +249,7 @@ static struct rs_control *init_rs_intern
    }

    /**
    - * init_rs - Find a matching or allocate a new rs control structure
    + * init_rs_gfp - Find a matching or allocate a new rs control structure
    * @symsize: the symbol size (number of bits)
    * @gfpoly: the extended Galois field generator polynomial coefficients,
    * with the 0th coefficient in the low order bit. The polynomial
    @@ -256,11 +258,12 @@ static struct rs_control *init_rs_intern
    * in index form
    * @prim: primitive element to generate polynomial roots
    * @nroots: RS code generator polynomial degree (number of roots)
    + * @gfp: GFP_ flags for allocations
    */
    -struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
    - int nroots)
    +struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
    + int nroots, gfp_t gfp)
    {
    - return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots);
    + return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots, gfp);
    }

    /**
    @@ -279,7 +282,8 @@ struct rs_control *init_rs(int symsize,
    struct rs_control *init_rs_non_canonical(int symsize, int (*gffunc)(int),
    int fcr, int prim, int nroots)
    {
    - return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots);
    + return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots,
    + GFP_KERNEL);
    }

    #ifdef CONFIG_REED_SOLOMON_ENC8

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