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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH RFC 2/2] libata: Use scsi cmnd budget token for qc tag for SAS host Content-Language: en-US To: John Garry , jejb@linux.ibm.com, martin.petersen@oracle.com, bvanassche@acm.org, ming.lei@redhat.com, hch@lst.de, hare@suse.de Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, martin.wilck@suse.com References: <1647340746-17600-1-git-send-email-john.garry@huawei.com> <1647340746-17600-3-git-send-email-john.garry@huawei.com> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <1647340746-17600-3-git-send-email-john.garry@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/15/22 19:39, John Garry wrote: > For attaining a qc tag for a SAS host we need to allocate a bit in > ata_port.sas_tag_allocated bitmap. > > However we already have a unique tag per device in range > [0, ATA_MAX_QUEUE) in the scsi cmnd budget token, so just use that > instead. > > Signed-off-by: John Garry > --- > drivers/ata/libata-core.c | 5 +++-- > drivers/ata/libata-sata.c | 21 ++++----------------- > drivers/ata/libata-scsi.c | 2 +- > drivers/ata/libata.h | 4 ++-- > include/linux/libata.h | 1 - > 5 files changed, 10 insertions(+), 23 deletions(-) > > diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c > index 0c854aebfe0b..2c0a550d3ecd 100644 > --- a/drivers/ata/libata-core.c > +++ b/drivers/ata/libata-core.c > @@ -4572,8 +4572,9 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words) > * None. > */ > > -struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag) > +struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, struct scsi_cmnd *scmd) > { > + int tag = scsi_cmd_to_rq(scmd)->tag; > struct ata_port *ap = dev->link->ap; > struct ata_queued_cmd *qc; > > @@ -4583,7 +4584,7 @@ struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag) > > /* libsas case */ > if (ap->flags & ATA_FLAG_SAS_HOST) { > - tag = ata_sas_allocate_tag(ap); > + tag = ata_sas_allocate_tag(ap, scmd); > if (tag < 0) > return NULL; > } > diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c > index 071158c0c44c..a4374fdffc43 100644 > --- a/drivers/ata/libata-sata.c > +++ b/drivers/ata/libata-sata.c > @@ -1268,29 +1268,16 @@ int ata_sas_queuecmd(struct scsi_cmnd *cmd, struct ata_port *ap) > } > EXPORT_SYMBOL_GPL(ata_sas_queuecmd); > > -int ata_sas_allocate_tag(struct ata_port *ap) > +int ata_sas_allocate_tag(struct ata_port *ap, struct scsi_cmnd *scmd) > { > - unsigned int max_queue = ap->host->n_tags; > - unsigned int i, tag; > + if (scmd->budget_token >= ATA_MAX_QUEUE) > + return -1; > > - for (i = 0, tag = ap->sas_last_tag + 1; i < max_queue; i++, tag++) { > - tag = tag < max_queue ? tag : 0; > - > - /* the last tag is reserved for internal command. */ > - if (ata_tag_internal(tag)) > - continue; > - > - if (!test_and_set_bit(tag, &ap->sas_tag_allocated)) { > - ap->sas_last_tag = tag; > - return tag; > - } > - } > - return -1; > + return scmd->budget_token; > } Since this is now not actually allocating a tag, I would rename this something like ata_sas_get_tag(). Or even better, simply open code this in ata_qc_new_init() since that is the only caller. > > void ata_sas_free_tag(unsigned int tag, struct ata_port *ap) > { > - clear_bit(tag, &ap->sas_tag_allocated); > } This is called only in ata_qc_free(). With this change, the function is empty, so let's completely remove it. > > /** > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > index ed8be585a98f..45d63a2ba3ee 100644 > --- a/drivers/ata/libata-scsi.c > +++ b/drivers/ata/libata-scsi.c > @@ -640,7 +640,7 @@ static struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev, > { > struct ata_queued_cmd *qc; > > - qc = ata_qc_new_init(dev, scsi_cmd_to_rq(cmd)->tag); > + qc = ata_qc_new_init(dev, cmd); > if (qc) { > qc->scsicmd = cmd; > qc->scsidone = scsi_done; > diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h > index 51e01acdd241..65302d7829fe 100644 > --- a/drivers/ata/libata.h > +++ b/drivers/ata/libata.h > @@ -44,7 +44,7 @@ static inline void ata_force_cbl(struct ata_port *ap) { } > #endif > extern u64 ata_tf_to_lba(const struct ata_taskfile *tf); > extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf); > -extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag); > +extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, struct scsi_cmnd *scmd); > extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev, > u64 block, u32 n_block, unsigned int tf_flags, > unsigned int tag, int class); > @@ -93,7 +93,7 @@ extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log, > > /* libata-sata.c */ > #ifdef CONFIG_SATA_HOST > -int ata_sas_allocate_tag(struct ata_port *ap); > +int ata_sas_allocate_tag(struct ata_port *ap, struct scsi_cmnd *scmd); > void ata_sas_free_tag(unsigned int tag, struct ata_port *ap); > #else > static inline int ata_sas_allocate_tag(struct ata_port *ap) > diff --git a/include/linux/libata.h b/include/linux/libata.h > index 7f99b4d78822..3b9399f67b39 100644 > --- a/include/linux/libata.h > +++ b/include/linux/libata.h > @@ -814,7 +814,6 @@ struct ata_port { > unsigned int cbl; /* cable type; ATA_CBL_xxx */ > > struct ata_queued_cmd qcmd[ATA_MAX_QUEUE + 1]; > - unsigned long sas_tag_allocated; /* for sas tag allocation only */ > u64 qc_active; > int nr_active_links; /* #links with active qcs */ > unsigned int sas_last_tag; /* track next tag hw expects */ -- Damien Le Moal Western Digital Research