Re: [PATCH 2/5] powerpc: ftrace, convert to new dynamic ftrace arch API
flat view
From: Paul Mackerras <hidden>
Date: 2008-11-24 02:35:18
Also in:
lkml
Steven Rostedt writes:
Thanks to Paul Mackennas for pointing out the mistakes of my original
Mackerras
quoted hunk ↗ jump to hunk
+static int test_24bit_addr(unsigned long ip, unsigned long addr) +{ + long diff; + + /* + * Can we get to addr from ip in 24 bits? + * (26 really, since we mulitply by 4 for 4 byte alignment) + */ + diff = addr - ip; + + /* + * Return true if diff is less than 1 << 25 + * and greater than -1 << 26. + */ + return (diff < (1 << 25)) && (diff > (-1 << 26));
I think this still isn't right, and the comment is one of those ones that is only useful to people who can't read C, as it's just a transliteration of the code. The comment should say something like "Return true if diff can be represented as a 26-bit twos-complement binary number" and the second part of the test should be (diff >= (-1 << 25)). However, since you define a test_offset() function in patch 4/5 that does the same test but using only one comparison instead of two, why don't you just say: return !test_offset(diff); (having first moved test_offset() before test_24bit_addr)? Paul.