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bh=nK7v3iVAGBAaAFOk1b449WFvKlocBCO05/yVMzqW7y0=; b=QQtGt54LoluqXGtBJyUsYl+J8K 6kg5fETS6rR2KHtQ3iZ1MnQTZnXolmL4Z5dWBQcT0+rZFJ8JwGcLzLcQZ2CMoNESc3bYgnyw9geNY 5WL52Dashy9KHEM31MV+uaDrPEAvgHzUCBVNUtJv+jhwJ0OTHCKGTFvWLOn6ACs6Qt8z2FdanJPOA PSXPFCi3p0ZyJ/jP5KOh5369P9p57Pubwh/3nTO1J8MctcbLlIORr52au3+EUpzLkXc9KGj5Cs5Sv Ln1XJydA3ocosqTpRq7bRzKtCMA6ZokRxi/aHXyblWJ6o6hcAtO5hGFAcZqd4FMS90SATtYNgs3bv 04U28J+Q==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1phSR5-00HMbf-0W; Wed, 29 Mar 2023 09:49:43 +0000 Date: Wed, 29 Mar 2023 02:49:43 -0700 From: Luis Chamberlain To: Peter Zijlstra Cc: david@redhat.com, patches@lists.linux.dev, linux-modules@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, pmladek@suse.com, petr.pavlu@suse.com, prarit@redhat.com, torvalds@linux-foundation.org, gregkh@linuxfoundation.org, rafael@kernel.org, christophe.leroy@csgroup.eu, tglx@linutronix.de, song@kernel.org, rppt@kernel.org, willy@infradead.org, vbabka@suse.cz, mhocko@suse.com, dave.hansen@linux.intel.com Subject: Re: [PATCH 4/7] sempahore: add a helper for a concurrency limiter Message-ID: References: <20230329053149.3976378-1-mcgrof@kernel.org> <20230329053149.3976378-5-mcgrof@kernel.org> <20230329072112.GG4253@hirez.programming.kicks-ass.net> <20230329091935.GP4253@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230329091935.GP4253@hirez.programming.kicks-ass.net> X-Rspamd-Queue-Id: A188240018 X-Stat-Signature: yd7awudaus1ithkwmca48f5ku7rji5zx X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1680083388-615893 X-HE-Meta: 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 Hx5t/ByC WbKsqSFZj3f2rXWmdQdZZu+74ZaI8668IkrD3BG/SVhJTN6qHZ4ExOglzHHj9YUiaS8pAsFc+ZIxN952EzjcC4ajAOUsYsGG1MEYbKFloXKZUOx0fs/+ml1Z5NAmGdYAfE85M/ny68+2FIJLRgLjZ8NG/3MvAA59rdIOMrW4uXKBU24crGB0gfuTQjb1jfBAeCAUlm1CqRv+3gSCV8vkdjic/bU1L/BiWWefY9ay+Xta5Nz5zPNxvxxIhVDMN0WIPIp0r74990JobQKbtx6cOyhKOyGrVJCOHh4lvdS/pQZAENXpOiXJMHj6Xs5z49Kp2P2GsaFz6OadUL9F2IClwSzLPoRHvsWwD8Q0G0bn87OZvBxbvae1AaNnj8cVP5LHvSOBbzxOg3egkzKZNry+R1vj/tvPLx9M2m401+mxDnOpnOr5jGtgL+TjMccjUbL6Qrjr1bxdZal+fKn4gMVWvVzQavg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 29, 2023 at 11:19:35AM +0200, Peter Zijlstra wrote: > On Wed, Mar 29, 2023 at 12:51:48AM -0700, Luis Chamberlain wrote: > > On Wed, Mar 29, 2023 at 09:21:12AM +0200, Peter Zijlstra wrote: > > > On Tue, Mar 28, 2023 at 10:31:46PM -0700, Luis Chamberlain wrote: > > > > While I looked at re-using the old kernel/kmod.c (now kernel/module/kmod.c) > > > > concurrency delimiter methodology for another place in the kernel Linus > > > > noted that this could be simply replaced with a sempahore [0]. > > > > > > > > So add that so we we don't re-invent the wheel and make it obvious to use. > > > > > > > > [0] https://lore.kernel.org/all/CAHk-=whkj6=wyi201JXkw9iT_eTUTsSx+Yb9d4OgmZFjDJA18g@mail.gmail.com/ > > > > > > > > Suggested-by: Linus Torvalds > > > > Signed-off-by: Luis Chamberlain > > > > --- > > > > include/linux/semaphore.h | 3 +++ > > > > 1 file changed, 3 insertions(+) > > > > > > > > diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h > > > > index 6694d0019a68..2ecdffdb9814 100644 > > > > --- a/include/linux/semaphore.h > > > > +++ b/include/linux/semaphore.h > > > > @@ -28,6 +28,9 @@ struct semaphore { > > > > #define DEFINE_SEMAPHORE(name) \ > > > > struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1) > > > > > > > > +#define CONCURRENCY_LIMITER(name, n) \ > > > > + struct semaphore name = __SEMAPHORE_INITIALIZER(name, n) > > > > + > > > > > > Why should this live in semaphore.h? > > > > I have no preference, but sharing seems to have been better. Do you > > have any recommendations? > > Call is DEFINE_SEMAPHORE_N() ? > > Arguably DEFINE_SEMAPHORE() should have the argument, as binary > semaphores are a special case, but then we gotta go and fix up all > users. > > /me git-greps a little.. Hmm, not too bad. > > How's this? Seems OK to me. Either way works. Should I carry a patch from you for this series? Luis