* gcc tickets for sparse attributes
@ 2014-01-17 5:27 H. Peter Anvin
2014-01-17 5:35 ` H. Peter Anvin
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: H. Peter Anvin @ 2014-01-17 5:27 UTC (permalink / raw)
To: Linux-Sparse; +Cc: Linux Kernel Mailing List
Hi,
I have filed gcc tickets asking for direct support in gcc for some
sparse extensions that we use heavily in the kernel:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59850
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59851
However, I would also like support for the context extensions, but I'm
not knowledgeable enough to describe the semantics accurately. Would
anyone be willing to file a ticket describing how the context extension
works well enough that it could be implemented?
-hpa
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: gcc tickets for sparse attributes 2014-01-17 5:27 gcc tickets for sparse attributes H. Peter Anvin @ 2014-01-17 5:35 ` H. Peter Anvin 2014-01-17 8:33 ` Johannes Berg 2014-01-17 9:18 ` Josh Triplett 2 siblings, 0 replies; 6+ messages in thread From: H. Peter Anvin @ 2014-01-17 5:35 UTC (permalink / raw) To: Linux-Sparse; +Cc: Linux Kernel Mailing List On 01/16/2014 09:27 PM, H. Peter Anvin wrote: > Hi, > > I have filed gcc tickets asking for direct support in gcc for some > sparse extensions that we use heavily in the kernel: > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59850 > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59851 > Add: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59852 -hpa ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: gcc tickets for sparse attributes 2014-01-17 5:27 gcc tickets for sparse attributes H. Peter Anvin 2014-01-17 5:35 ` H. Peter Anvin @ 2014-01-17 8:33 ` Johannes Berg 2014-01-17 9:22 ` Josh Triplett 2014-01-17 9:18 ` Josh Triplett 2 siblings, 1 reply; 6+ messages in thread From: Johannes Berg @ 2014-01-17 8:33 UTC (permalink / raw) To: H. Peter Anvin; +Cc: Linux-Sparse, Linux Kernel Mailing List On Thu, 2014-01-16 at 21:27 -0800, H. Peter Anvin wrote: > However, I would also like support for the context extensions, but I'm > not knowledgeable enough to describe the semantics accurately. Would > anyone be willing to file a ticket describing how the context extension > works well enough that it could be implemented? IMHO the context extension doesn't work well enough in sparse to document and implement as is. It would be much better if it actually was able to differentiate between contexts, rather than treating each one the same. This would avoid the problem that locking one lock and unlocking another (in the kernel's __acquire/ __release mechanism) could still result in a warning. johannes ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: gcc tickets for sparse attributes 2014-01-17 8:33 ` Johannes Berg @ 2014-01-17 9:22 ` Josh Triplett 2014-01-17 10:23 ` Johannes Berg 0 siblings, 1 reply; 6+ messages in thread From: Josh Triplett @ 2014-01-17 9:22 UTC (permalink / raw) To: Johannes Berg; +Cc: H. Peter Anvin, Linux-Sparse, Linux Kernel Mailing List On Fri, Jan 17, 2014 at 09:33:16AM +0100, Johannes Berg wrote: > On Thu, 2014-01-16 at 21:27 -0800, H. Peter Anvin wrote: > > > However, I would also like support for the context extensions, but I'm > > not knowledgeable enough to describe the semantics accurately. Would > > anyone be willing to file a ticket describing how the context extension > > works well enough that it could be implemented? > > IMHO the context extension doesn't work well enough in sparse to > document and implement as is. It would be much better if it actually was > able to differentiate between contexts, rather than treating each one > the same. That would certainly be nice, but that's something actually much more easily done in GCC than in Sparse, given the types of information GCC already has available to implement features like alias analysis. In any case, the spec I wrote up assumes a distinction between contexts, but allows for an initial implementation like Sparse's that ignores the distinction. > This would avoid the problem that locking one lock and > unlocking another (in the kernel's __acquire/ __release mechanism) could > still result in a warning. That would actually *not* produce a warning, though it should. In general, I *think* an implementation like Sparse's that ignores the distinction between locks should produce false negatives but not false positives. - Josh Triplett ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: gcc tickets for sparse attributes 2014-01-17 9:22 ` Josh Triplett @ 2014-01-17 10:23 ` Johannes Berg 0 siblings, 0 replies; 6+ messages in thread From: Johannes Berg @ 2014-01-17 10:23 UTC (permalink / raw) To: Josh Triplett; +Cc: H. Peter Anvin, Linux-Sparse, Linux Kernel Mailing List > > IMHO the context extension doesn't work well enough in sparse to > > document and implement as is. It would be much better if it actually was > > able to differentiate between contexts, rather than treating each one > > the same. > > That would certainly be nice, but that's something actually much more > easily done in GCC than in Sparse, given the types of information GCC > already has available to implement features like alias analysis. Right. > In any case, the spec I wrote up assumes a distinction between contexts, > but allows for an initial implementation like Sparse's that ignores the > distinction. Ok cool. :) > > This would avoid the problem that locking one lock and > > unlocking another (in the kernel's __acquire/ __release mechanism) could > > still result in a warning. > > That would actually *not* produce a warning, though it should. In > general, I *think* an implementation like Sparse's that ignores the > distinction between locks should produce false negatives but not false > positives. Right, it doesn't report one now. johannes ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: gcc tickets for sparse attributes 2014-01-17 5:27 gcc tickets for sparse attributes H. Peter Anvin 2014-01-17 5:35 ` H. Peter Anvin 2014-01-17 8:33 ` Johannes Berg @ 2014-01-17 9:18 ` Josh Triplett 2 siblings, 0 replies; 6+ messages in thread From: Josh Triplett @ 2014-01-17 9:18 UTC (permalink / raw) To: H. Peter Anvin; +Cc: Linux-Sparse, Linux Kernel Mailing List On Thu, Jan 16, 2014 at 09:27:08PM -0800, H. Peter Anvin wrote: > I have filed gcc tickets asking for direct support in gcc for some > sparse extensions that we use heavily in the kernel: > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59850 > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59851 > > However, I would also like support for the context extensions, but I'm > not knowledgeable enough to describe the semantics accurately. Would > anyone be willing to file a ticket describing how the context extension > works well enough that it could be implemented? http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59856 Also: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59855 - Josh Triplett ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-01-17 10:23 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-01-17 5:27 gcc tickets for sparse attributes H. Peter Anvin 2014-01-17 5:35 ` H. Peter Anvin 2014-01-17 8:33 ` Johannes Berg 2014-01-17 9:22 ` Josh Triplett 2014-01-17 10:23 ` Johannes Berg 2014-01-17 9:18 ` Josh Triplett
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