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Fri, 4 Sep 2026 17:58:17 -0400 (EDT) Date: Fri, 4 Sep 2026 23:58:16 +0200 From: Jesper Wendel Devantier To: Daniel Gomez Cc: qemu-devel@nongnu.org, Paolo Bonzini , Peter Xu , Philippe Mathieu-Daudé , Keith Busch , Klaus Jensen , Klaus Jensen , qemu-block@nongnu.org, Daniel Gomez , GOST Subject: Re: [PATCH v2 4/7] dma-helpers: chunk dma_blk_cb at IOV_MAX Message-ID: <20260904235802.4-foss@defmacro.it> In-Reply-To: <20260819-align-nvme-mdts-with-linux-v2-4-351ac2dfed64@samsung.com> References: <20260819-align-nvme-mdts-with-linux-v2-0-351ac2dfed64@samsung.com> <20260819-align-nvme-mdts-with-linux-v2-4-351ac2dfed64@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 X-Mailer: lorebird Received-SPF: pass client-ip=103.168.172.158; envelope-from=foss@defmacro.it; helo=fhigh-a7-smtp.messagingengine.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2026-08-19T17:24:06+02:00, Daniel Gomez wrote: > From: Daniel Gomez > > dma_blk_cb() submits dbs->iov to io_func() in one shot, so callers > must keep dbs->iov.niov below IOV_MAX or the host preadv()/pwritev() > rejects the call. > > Break the accumulation loop when niov reaches IOV_MAX. The existing > re-entry path resumes mapping and submits a follow-up chunk under > the same AIOCB, so callers no longer carry that constraint. > > Suggested-by: Klaus Jensen > Signed-off-by: Daniel Gomez > --- > system/dma-helpers.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/system/dma-helpers.c b/system/dma-helpers.c > index d4fd33a3d4c..613fa548669 100644 > --- a/system/dma-helpers.c > +++ b/system/dma-helpers.c > @@ -175,6 +175,9 @@ static void dma_blk_cb(void *opaque, int ret) > dbs->sg_cur_byte = 0; > ++dbs->sg_cur_index; > } > + if (dbs->iov.niov >= IOV_MAX) { > + break; > + } > } > > if (dbs->iov.size == 0) { > > -- > 2.55.0 > > > Acked-by: Jesper Wendel Devantier