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[73.241.217.19]) by smtp.gmail.com with ESMTPSA id 199sm11480185pgc.79.2020.06.24.06.33.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Jun 2020 06:33:19 -0700 (PDT) Subject: Re: [PATCH] scsi: sd: add runtime pm to open / release To: Martin Kepplinger , jejb@linux.ibm.com, martin.petersen@oracle.com Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@puri.sm References: <20200623111018.31954-1-martin.kepplinger@puri.sm> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: Date: Wed, 24 Jun 2020 06:33:17 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200623111018.31954-1-martin.kepplinger@puri.sm> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-06-23 04:10, Martin Kepplinger wrote: > This add a very conservative but simple implementation for runtime PM > to the sd scsi driver: > Resume when opened (mounted) and suspend when released (unmounted). > > Improvements that allow suspending while a device is "open" can > be added later, but now we save power when no filesystem is mounted > and runtime PM is enabled. > > Signed-off-by: Martin Kepplinger > --- > drivers/scsi/sd.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index d90fefffe31b..fe4cb7c50ec1 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -1372,6 +1372,7 @@ static int sd_open(struct block_device *bdev, fmode_t mode) > SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_open\n")); > > sdev = sdkp->device; > + scsi_autopm_get_device(sdev); > > /* > * If the device is in error recovery, wait until it is done. > @@ -1418,6 +1419,9 @@ static int sd_open(struct block_device *bdev, fmode_t mode) > > error_out: > scsi_disk_put(sdkp); > + > + scsi_autopm_put_device(sdev); > + > return retval; > } > > @@ -1441,6 +1445,8 @@ static void sd_release(struct gendisk *disk, fmode_t mode) > > SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_release\n")); > > + scsi_autopm_put_device(sdev); > + > if (atomic_dec_return(&sdkp->openers) == 0 && sdev->removable) { > if (scsi_block_when_processing_errors(sdev)) > scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW); My understanding of the above patch is that it introduces a regression, namely by disabling runtime suspend as long as an sd device is held open. Bart.