RE: [PATCH v4 2/6] treewide: use prandom_u32_max() when possible
From: David Laight <hidden>
Date: 2022-10-08 22:09:31
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From: Jason A. Donenfeld
Sent: 07 October 2022 19:01 Rather than incurring a division or requesting too many random bytes for the given range, use the prandom_u32_max() function, which only takes the minimum required bytes from the RNG and avoids divisions.
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quoted hunk ↗ jump to hunk
--- a/lib/cmdline_kunit.c +++ b/lib/cmdline_kunit.c@@ -76,7 +76,7 @@ static void cmdline_test_lead_int(struct kunit *test) int rc = cmdline_test_values[i]; int offset; - sprintf(in, "%u%s", prandom_u32_max(256), str); + sprintf(in, "%u%s", get_random_int() % 256, str); /* Only first '-' after the number will advance the pointer */ offset = strlen(in) - strlen(str) + !!(rc == 2); cmdline_do_one_test(test, in, rc, offset);@@ -94,7 +94,7 @@ static void cmdline_test_tail_int(struct kunit *test) int rc = strcmp(str, "") ? (strcmp(str, "-") ? 0 : 1) : 1; int offset; - sprintf(in, "%s%u", str, prandom_u32_max(256)); + sprintf(in, "%s%u", str, get_random_int() % 256); /* * Only first and leading '-' not followed by integer * will advance the pointer.
Something has gone backwards here.... And get_random_u8() looks a better fit. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)