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Thu, 9 Jul 2020 08:31:39 +0000 From: Avri Altman To: Stanley Chu , "linux-scsi@vger.kernel.org" , "martin.petersen@oracle.com" , "alim.akhtar@samsung.com" , "jejb@linux.ibm.com" , "bvanassche@acm.org" CC: "beanhuo@micron.com" , "asutoshd@codeaurora.org" , "cang@codeaurora.org" , "matthias.bgg@gmail.com" , "linux-mediatek@lists.infradead.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "kuohong.wang@mediatek.com" , "peter.wang@mediatek.com" , "chun-hung.wu@mediatek.com" , "andy.teng@mediatek.com" , "chaotian.jing@mediatek.com" , "cc.chou@mediatek.com" Subject: RE: [PATCH v3] scsi: ufs: Cleanup completed request without interrupt notification Thread-Topic: [PATCH v3] scsi: ufs: Cleanup completed request without interrupt notification Thread-Index: AQHWU5heDqJFApuOo0yQOIjuO+/O36j+4j7g Date: Thu, 9 Jul 2020 08:31:38 +0000 Message-ID: References: <20200706132113.21096-1-stanley.chu@mediatek.com> In-Reply-To: <20200706132113.21096-1-stanley.chu@mediatek.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: mediatek.com; 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x-ms-exchange-antispam-messagedata: VB7j0/TJzQVR6fomZg8zgSw2HNqIn0PNt1thFo7ijLLYY2XFOBjlQeqjGMm6EXMVVeeAqHkoRVSwwOj6zo3ICVtfdTQtzRrfUUMikrbEn5MymvEX3orIjhq/xRZI61GJujBXNSkIw2ZR8zSz49auqHwN8BJEtuh3RjaWt2SpF1iSyfw5bKUWR6GrRZKxoAcMPes6suQDXIMt4yvNwLfSYB6+/RFAFDyJD5R+xOUgj7T3oFbiTpIpBlNpSMxWSYmJxEPD97wSUvm6pGKzXbtliaFmVHxNDwEMTK3mdM5YhY3tk+btsrr49jAb/Bq/ypd42KI5EUWp3jeNwQDRDxpRIfh75XuofTMxx61H2JkSaj8F43Wh3FZrZsO0t96hOnAq5Wo8o4eweN54iB3fibC7K4ETuh1wD7sDbf4hdCircb5BUsGyJXKjsldMyaV0503pUWww4a1+7XtZZSn+RbQrmXtRaXUUjqBiiM7LbNJzDhA= x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: SN6PR04MB4640.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 665e6441-f06d-4590-f60a-08d823e28001 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Jul 2020 08:31:38.8429 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 2cq1zmKEfR9AqZypCwZzRcsU2LIeDFUYQcaCsBQHhFDuXdQ6trcxb+lNRtWAEm8Fr0zG5EVBQ8bOvK+uXIU02w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR04MB3997 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org =20 >=20 > If somehow no interrupt notification is raised for a completed request > and its doorbell bit is cleared by host, UFS driver needs to cleanup > its outstanding bit in ufshcd_abort(). Theoretically, this case is already accounted for -=20 See line 6407: a proper error is issued and eventually outstanding req is c= leared. Can you go over the scenario you are attending line by line, And explain why ufshcd_abort does not account for it? >=20 > Otherwise, system may crash by below abnormal flow: >=20 > After this request is requeued by SCSI layer with its > outstanding bit set, the next completed request will trigger > ufshcd_transfer_req_compl() to handle all "completed outstanding > bits". In this time, the "abnormal outstanding bit" will be detected > and the "requeued request" will be chosen to execute request > post-processing flow. This is wrong and blk_finish_request() will > BUG_ON because this request is still "alive". >=20 > It is worth mentioning that before ufshcd_abort() cleans the timed-out > request, driver need to check again if this request is really not > handled by __ufshcd_transfer_req_compl() yet because it may be > possible that the interrupt comes very lately before the cleaning. What do you mean? Why checking the outstanding reqs isn't enough? >=20 > Signed-off-by: Stanley Chu > --- > drivers/scsi/ufs/ufshcd.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index 8603b07045a6..f23fb14df9f6 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -6462,7 +6462,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) > /* command completed already */ > dev_err(hba->dev, "%s: cmd at tag %d successfully= cleared from > DB.\n", > __func__, tag); > - goto out; > + goto cleanup; But you've arrived here only if (!(test_bit(tag, &hba->outstanding_reqs))) = -=20 See line 6400.=20 > } else { > dev_err(hba->dev, > "%s: no response from device. tag =3D %d,= err %d\n", > @@ -6496,9 +6496,14 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) > goto out; > } >=20 > +cleanup: > + spin_lock_irqsave(host->host_lock, flags); > + if (!test_bit(tag, &hba->outstanding_reqs)) { > + spin_unlock_irqrestore(host->host_lock, flags); > + goto out; > + } > scsi_dma_unmap(cmd); >=20 > - spin_lock_irqsave(host->host_lock, flags); > ufshcd_outstanding_req_clear(hba, tag); > hba->lrb[tag].cmd =3D NULL; > spin_unlock_irqrestore(host->host_lock, flags); > -- > 2.18.0