diff options
Diffstat (limited to 'bfq-lock-division-zero.patch')
| -rw-r--r-- | bfq-lock-division-zero.patch | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/bfq-lock-division-zero.patch b/bfq-lock-division-zero.patch new file mode 100644 index 000000000000..e8d8727d5117 --- /dev/null +++ b/bfq-lock-division-zero.patch @@ -0,0 +1,35 @@ +Rate should never overflow or become zero because it is used as divider. +This patch accumulates it with saturation. + +Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> +--- + block/bfq-iosched.c | 8 +++++--- + 1 file changed, 5 insertions(+), 3 deletions(-) + +diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c +index aeca22d91101..a236c8d541b5 100644 +--- a/block/bfq-iosched.c ++++ b/block/bfq-iosched.c +@@ -2546,7 +2546,8 @@ static void bfq_reset_rate_computation(struct bfq_data *bfqd, + + static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq) + { +- u32 rate, weight, divisor; ++ u32 weight, divisor; ++ u64 rate; + + /* + * For the convergence property to hold (see comments on +@@ -2634,9 +2635,10 @@ static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq) + */ + bfqd->peak_rate *= divisor-1; + bfqd->peak_rate /= divisor; +- rate /= divisor; /* smoothing constant alpha = 1/divisor */ ++ do_div(rate, divisor); /* smoothing constant alpha = 1/divisor */ + +- bfqd->peak_rate += rate; ++ /* rate should never overlow or become zero */ ++ bfqd->peak_rate = clamp_t(u64, rate + bfqd->peak_rate, 1, U32_MAX); + update_thr_responsiveness_params(bfqd); + + reset_computation: |