>> So you are saying that this presents an unrecoverable situation? > > No, I'm saying that the data phase need not have a bunch of in-kernel > checks, it should be generated correctly from the source. The SCSI drivers validate the controller's data phase based on the expected phase presented to them from an upper layer. I never talked about adding checks that make little sense or are overly expensive. You seem to equate validation with huge expense. That is just not the general case. >> Hmm. I've never had someone tell me that my SCSI drivers are slow. > > This would be noticed in the CPU utilization area. Your drivers are > probably a long way from being CPU-bound. I very much doubt that. There are perhaps four or five tests in the I/O path where some value already in a cache line that has to be accessed anyway is compared against a constant. We're talking about something down in the noise of any type of profiling you could perform. As I said, validation makes sense where there is basically no-cost to do it. >> I don't think that your statement is true in the general case. My >> belief is that validation should occur where it is cheap and efficient >> to do so. More expensive checks should be pushed into diagnostic code >> that is disabled by default, but the code *should be there*. In any event, >> for RAID meta-data, we're talking about code that is *not* in the common >> or time critical path of the kernel. A few dozen lines of validation code >> there has almost no impact on the size of the kernel and yields huge >> benefits for debugging and maintaining the code. This is even more >> the case in Linux the end user is often your test lab. > > It doesn't scale terribly well, because the checks themselves become a > source of bugs. So now the complaint is that validation code is somehow harder to write and maintain than the rest of the code? -- Justin - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
