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[34.142.255.199]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-137f5550bcdsm13363034c88.14.2026.06.08.11.10.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2026 11:10:09 -0700 (PDT) Date: Mon, 8 Jun 2026 18:10:02 +0000 From: Pranjal Shrivastava To: Samiullah Khawaja Cc: Marek Szyprowski , Will Deacon , Jason Gunthorpe , Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Alexander Graf , Robin Murphy , Kevin Tian , iommu@lists.linux.dev, kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Matlack , Andrew Morton , Vipin Sharma Subject: Re: [RFC PATCH 2/4] dma/pool: Add an API to check if DMA allocation is from pool Message-ID: References: <20260505002737.2213734-1-skhawaja@google.com> <20260505002737.2213734-3-skhawaja@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260505002737.2213734-3-skhawaja@google.com> On Tue, May 05, 2026 at 12:27:35AM +0000, Samiullah Khawaja wrote: > DMA allocations can be done through DMA pools, add an API that can be > used to check if an allocation is done from a pool. This will be used in > the later commit during preservation of DMA allocation. > > Signed-off-by: Samiullah Khawaja > --- > include/linux/dma-map-ops.h | 1 + > kernel/dma/pool.c | 13 +++++++++++++ > 2 files changed, 14 insertions(+) > > diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h > index 6a1832a73cad..6a0bc4ea2467 100644 > --- a/include/linux/dma-map-ops.h > +++ b/include/linux/dma-map-ops.h > @@ -216,6 +216,7 @@ struct page *dma_alloc_from_pool(struct device *dev, size_t size, > bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t)); > bool dma_free_from_pool(struct device *dev, void *start, size_t size); > > +bool dma_is_from_pool(struct device *dev, void *start, size_t size); > int dma_direct_set_offset(struct device *dev, phys_addr_t cpu_start, > dma_addr_t dma_start, u64 size); > > diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c > index 2b2fbb709242..32ce4d6d7683 100644 > --- a/kernel/dma/pool.c > +++ b/kernel/dma/pool.c > @@ -307,3 +307,16 @@ bool dma_free_from_pool(struct device *dev, void *start, size_t size) > > return false; > } > + > +bool dma_is_from_pool(struct device *dev, void *start, size_t size) Do we need struct device here? It seems unused? Nit: we only ever pass 0 gfp_flags to dma_guess_pool, should we instead name it: dma_is_from_atomic_pool() to be more accurate? > +{ > + struct gen_pool *pool = NULL; > + > + while ((pool = dma_guess_pool(pool, 0))) { > + if (!gen_pool_has_addr(pool, (unsigned long)start, size)) > + continue; > + return true; > + } Nit: The loop looks slightly ugly, can we have: struct gen_pool *pool; for (pool = dma_guess_pool(NULL, 0); pool != NULL; pool = dma_guess_pool(pool, 0)) { if (gen_pool_has_addr(pool, (unsigned long)start, size)) return true; } > + > + return false; > +} > -- > 2.54.0.545.g6539524ca2-goog > Thanks, Praan