diff options
| -rw-r--r-- | include/linux/rslib.h | 2 | ||||
| -rw-r--r-- | lib/reed_solomon/decode_rs.c | 20 | ||||
| -rw-r--r-- | lib/reed_solomon/reed_solomon.c | 31 |
3 files changed, 45 insertions, 8 deletions
diff --git a/include/linux/rslib.h b/include/linux/rslib.h index 6703311..5974ced 100644 --- a/include/linux/rslib.h +++ b/include/linux/rslib.h @@ -50,9 +50,11 @@ struct rs_codec { /** * struct rs_control - rs control structure per instance * @codec: The codec used for this instance + * @buffers: Internal scratch buffers used in calls to decode_rs() */ struct rs_control { struct rs_codec *codec; + uint16_t buffers[0]; }; /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c index 794cced..1db74eb 100644 --- a/lib/reed_solomon/decode_rs.c +++ b/lib/reed_solomon/decode_rs.c @@ -21,16 +21,22 @@ uint16_t *alpha_to = rs->alpha_to; uint16_t *index_of = rs->index_of; uint16_t u, q, tmp, num1, num2, den, discr_r, syn_error; - /* Err+Eras Locator poly and syndrome poly The maximum value - * of nroots is 8. So the necessary stack size will be about - * 220 bytes max. - */ - uint16_t lambda[nroots + 1], syn[nroots]; - uint16_t b[nroots + 1], t[nroots + 1], omega[nroots + 1]; - uint16_t root[nroots], reg[nroots + 1], loc[nroots]; int count = 0; uint16_t msk = (uint16_t) rs->nn; + /* + * The decoder buffers are in the rs control struct. They are + * arrays sized [nroots + 1] + */ + uint16_t *lambda = rsc->buffers + RS_DECODE_LAMBDA * (nroots + 1); + uint16_t *syn = rsc->buffers + RS_DECODE_SYN * (nroots + 1); + uint16_t *b = rsc->buffers + RS_DECODE_B * (nroots + 1); + uint16_t *t = rsc->buffers + RS_DECODE_T * (nroots + 1); + uint16_t *omega = rsc->buffers + RS_DECODE_OMEGA * (nroots + 1); + uint16_t *root = rsc->buffers + RS_DECODE_ROOT * (nroots + 1); + uint16_t *reg = rsc->buffers + RS_DECODE_REG * (nroots + 1); + uint16_t *loc = rsc->buffers + RS_DECODE_LOC * (nroots + 1); + /* Check length parameter for validity */ pad = nn - nroots - len; BUG_ON(pad < 0 || pad >= nn); diff --git a/lib/reed_solomon/reed_solomon.c b/lib/reed_solomon/reed_solomon.c index cb21e8b..dfcf542 100644 --- a/lib/reed_solomon/reed_solomon.c +++ b/lib/reed_solomon/reed_solomon.c @@ -37,6 +37,18 @@ #include <linux/slab.h> #include <linux/mutex.h> +enum { + RS_DECODE_LAMBDA, + RS_DECODE_SYN, + RS_DECODE_B, + RS_DECODE_T, + RS_DECODE_OMEGA, + RS_DECODE_ROOT, + RS_DECODE_REG, + RS_DECODE_LOC, + RS_DECODE_NUM_BUFFERS +}; + /* This list holds all currently allocated rs codec structures */ static LIST_HEAD(codec_list); /* Protection for the list */ @@ -204,6 +216,7 @@ static struct rs_control *init_rs_internal(int symsize, int gfpoly, { struct list_head *tmp; struct rs_control *rs; + unsigned int bsize; /* Sanity checks */ if (symsize < 1) @@ -215,7 +228,13 @@ static struct rs_control *init_rs_internal(int symsize, int gfpoly, if (nroots < 0 || nroots >= (1<<symsize)) return NULL; - rs = kzalloc(sizeof(*rs), GFP_KERNEL); + /* + * The decoder needs buffers in each control struct instance to + * avoid variable size or large fixed size allocations on + * stack. Size the buffers to arrays of [nroots + 1]. + */ + bsize = sizeof(uint16_t) * RS_DECODE_NUM_BUFFERS * (nroots + 1); + rs = kzalloc(sizeof(*rs) + bsize, gfp); if (!rs) return NULL; @@ -330,6 +349,11 @@ EXPORT_SYMBOL_GPL(encode_rs8); * The syndrome and parity uses a uint16_t data type to enable * symbol size > 8. The calling code must take care of decoding of the * syndrome result and the received parity before calling this code. + * + * Note: The rs_control struct @rsc contains buffers which are used for + * decoding, so the caller has to ensure that decoder invocations are + * serialized. + * * Returns the number of corrected bits or -EBADMSG for uncorrectable errors. */ int decode_rs8(struct rs_control *rsc, uint8_t *data, uint16_t *par, int len, @@ -374,6 +398,11 @@ EXPORT_SYMBOL_GPL(encode_rs16); * @corr: buffer to store correction bitmask on eras_pos * * Each field in the data array contains up to symbol size bits of valid data. + * + * Note: The rc_control struct @rsc contains buffers which are used for + * decoding, so the caller has to ensure that decoder invocations are + * serialized. + * * Returns the number of corrected bits or -EBADMSG for uncorrectable errors. */ int decode_rs16(struct rs_control *rsc, uint16_t *data, uint16_t *par, int len, |
