Am 30.05.2007 17:41 schrieb Satyam Sharma: > On 5/30/07, Roland Dreier <[email protected]> wrote: >> thanks... I'm wondering if there's a consensus among kernel hackers >> about changes like: >> >> > - if (hdr.cmd < 0 || hdr.cmd >= ARRAY_SIZE(ucma_cmd_table)) >> > + if (hdr.cmd >= ARRAY_SIZE(ucma_cmd_table)) >> > return -EINVAL; >> >> I understand that new gcc sees that hdr.cmd is unsigned and hence >> can't be < 0, and generates a warning for that, and having a build >> cluttered with warnings hides bugs and so on. However the code here >> looks quite sensible to me -- otherwise we end up with missing range >> checking if hdr.cmd ever changes to a signed type. This seems like a >> good way to introduce bugs: delete valid range checking code to shut >> up a silly gcc warning, and then change the type of a variable. > > You're *absolutely* correct about the issue that these "fixes" that remove > such conditions end up remove range-checking making the code more > flakey / less readable. I disagree. Changing the type of a variable is a significant modification. If someone does that, he or she *must* check every use of that variable, at which point he or she will also modify any range checks accordingly. Having checks that don't fit with the previous type *distracts* from that job. "Oh, did I modify that part already? Guess I can skip checking the rest of that function then." Oops. Nor is readability a suitable argument. Checking if hdr.cmd is less than zero gives the misleading impression that it *could* be less than zero, thus *impairing* readability. jm2c T. -- Tilman Schmidt E-Mail: [email protected] Bonn, Germany Diese Nachricht besteht zu 100% aus wiederverwerteten Bits. Ungeöffnet mindestens haltbar bis: (siehe Rückseite)
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