linux-kernel - Re: [PATCH] nvmet: pci-epf: Do not complete commands twice if nvmet_req

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Message-ID: <5c038378-dd65-4a4d-9a5b-d3604769b658@kernel.org>
Date: Wed, 16 Jul 2025 08:22:54 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Rick Wertenbroek <rick.wertenbroek@...il.com>
Cc: rick.wertenbroek@...g-vd.ch, alberto.dassatti@...g-vd.ch,
 Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
 Chaitanya Kulkarni <kch@...dia.com>, linux-nvme@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nvmet: pci-epf: Do not complete commands twice if
 nvmet_req_init() fails

On 7/15/25 18:18, Rick Wertenbroek wrote:
> Have nvmet_req_init() and req->execute() complete failed commands.
> 
> Description of the problem:
> nvmet_req_init() calls __nvmet_req_complete() internally upon failure,
> e.g., unsupported opcode, which calls the "queue_response" callback,
> this results in nvmet_pci_epf_queue_response() being called, which will
> call nvmet_pci_epf_complete_iod() if data_len is 0 or if dma_dir is
> different than DMA_TO_DEVICE. This results in a double completion as
> nvmet_pci_epf_exec_iod_work() also calls nvmet_pci_epf_complete_iod()
> when nvmet_req_init() fails.
> 
> Steps to reproduce:
> On the host send a command with an unsupported opcode with nvme-cli,
> For example the admin command "security receive"
> $ sudo nvme security-recv /dev/nvme0n1 -n1 -x4096
> 
> This triggers a double completion as nvmet_req_init() fails and
> nvmet_pci_epf_queue_response() is called, here iod->dma_dir is still
> in the default state of "DMA_NONE" as set by default in
> nvmet_pci_epf_alloc_iod(), so nvmet_pci_epf_complete_iod() is called.
> Because nvmet_req_init() failed nvmet_pci_epf_complete_iod() is also
> called in nvmet_pci_epf_exec_iod_work() leading to a doubple completion.
> 
> This patch lets nvmet_req_init() and req->execute() complete all failed
> commands, and removes the double completion case in
> nvmet_pci_epf_exec_iod_work() therefore fixing the edge cases where
> double completions occurred.
> 
> Signed-off-by: Rick Wertenbroek <rick.wertenbroek@...il.com>

Forgot: this needs a fixes tag and cc-stable:

Fixes: 0faa0fe6f90e ("nvmet: New NVMe PCI endpoint function target driver")
Cc: stable@...r.kernel.org

-- 
Damien Le Moal
Western Digital Research