| Message ID | 1440679281-13234-18-git-send-email-hare@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> + * Internal error: TPGS supported by no > + * device identifcation found. > + * Disable ALUA support. s/by/but/ Also I think the comment could fit into two lines if you try :) > + spin_lock(&port_group_lock); > + list_for_each_entry(tmp_pg, &port_group_list, node) { > + if (tmp_pg->group_id != group_id) > + continue; > + if (tmp_pg->device_id_size != device_id_size) > + continue; > + if (strncmp(tmp_pg->device_id_str, device_id_str, > + device_id_size)) > + continue; > + h->pg = tmp_pg; > + kref_get(&tmp_pg->kref); > + break; > + } > + spin_unlock(&port_group_lock); This exact code appears twice in this patch, please factor it into a helper. > + if (device_id_size) > + strncpy(pg->device_id_str, device_id_str, 256); > + else > + pg->device_id_str[0] = '\0'; > + How could we end up with a zero device ID length? Shouldn't have error out earlier on that? > + * Re-check list again to catch > + * concurrent updates > + */ Could fit onto one line.. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 2015-08-27 at 14:41 +0200, Hannes Reinecke wrote: > Use scsi_vpd_lun_id() to assign a unique device identification > to the alua port group structure. > > Signed-off-by: Hannes Reinecke <hare@suse.de> > --- > drivers/scsi/device_handler/scsi_dh_alua.c | 70 +++++++++++++++++++++++++++--- > 1 file changed, 65 insertions(+), 5 deletions(-) > > diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c > index dbe9ff2..c2b2100b 100644 > --- a/drivers/scsi/device_handler/scsi_dh_alua.c > +++ b/drivers/scsi/device_handler/scsi_dh_alua.c > @@ -70,6 +70,8 @@ static DEFINE_SPINLOCK(port_group_lock); > struct alua_port_group { > struct kref kref; > struct list_head node; > + unsigned char device_id_str[256]; > + int device_id_size; I prefer _len instead of _size, _size should refer to the size of the buffer, not the current length of the data in it. > int group_id; > int tpgs; > int state; > @@ -229,7 +231,9 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) > { > unsigned char *d; > int group_id = -1; > - struct alua_port_group *pg = NULL; > + char device_id_str[256]; > + int device_id_size; > + struct alua_port_group *tmp_pg, *pg = NULL; > > if (!sdev->vpd_pg83) > return SCSI_DH_DEV_UNSUPP; > @@ -266,9 +270,39 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) > h->tpgs = TPGS_MODE_NONE; > return SCSI_DH_DEV_UNSUPP; > } > + device_id_size = scsi_vpd_lun_id(sdev, device_id_str, 256); should be sizeof(device_id_str) not hardcoded 256 > + if (device_id_size <= 0) { > + /* > + * Internal error: TPGS supported by no "Internal error: TPGS supported by no" should be "but no" > + * device identifcation found. > + * Disable ALUA support. > + */ > + sdev_printk(KERN_INFO, sdev, > + "%s: No device descriptors found\n", > + ALUA_DH_NAME); > + h->tpgs = TPGS_MODE_NONE; > + return SCSI_DH_DEV_UNSUPP; > + } > sdev_printk(KERN_INFO, sdev, > - "%s: port group %02x rel port %02x\n", > - ALUA_DH_NAME, group_id, h->rel_port); > + "%s: device %s port group %02x " > + "rel port %02x\n", ALUA_DH_NAME, > + device_id_str, group_id, h->rel_port); > + spin_lock(&port_group_lock); > + list_for_each_entry(tmp_pg, &port_group_list, node) { > + if (tmp_pg->group_id != group_id) > + continue; > + if (tmp_pg->device_id_size != device_id_size) > + continue; > + if (strncmp(tmp_pg->device_id_str, device_id_str, > + device_id_size)) > + continue; > + h->pg = tmp_pg; > + kref_get(&tmp_pg->kref); > + break; > + } > + spin_unlock(&port_group_lock); > + if (h->pg) > + return SCSI_DH_OK; The lookup checks whether h->pg == NULL but the function never explicitly sets it to NULL before iterating. > > pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL); > if (!pg) { > @@ -278,13 +312,39 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) > /* Temporary failure, bypass */ > return SCSI_DH_DEV_TEMP_BUSY; > } > + if (device_id_size) > + strncpy(pg->device_id_str, device_id_str, 256); should be sizeof(device_id_str) not hardcoded 256 > + else > + pg->device_id_str[0] = '\0'; > + > + pg->device_id_size = device_id_size; > pg->group_id = group_id; > pg->tpgs = h->tpgs; > pg->state = TPGS_STATE_OPTIMIZED; > kref_init(&pg->kref); > spin_lock(&port_group_lock); > - list_add(&pg->node, &port_group_list); > - h->pg = pg; > + /* > + * Re-check list again to catch > + * concurrent updates > + */ > + list_for_each_entry(tmp_pg, &port_group_list, node) { > + if (tmp_pg->group_id != pg->group_id) > + continue; > + if (tmp_pg->device_id_size != pg->device_id_size) > + continue; > + if (strncmp(tmp_pg->device_id_str, pg->device_id_str, > + device_id_size)) > + continue; > + h->pg = tmp_pg; > + kref_get(&tmp_pg->kref); > + kfree(pg); With the added check for an existing alua_port_group object, and the kfree() of the alua_port_group that had been allocated if an existing one is found, the code does not do a destroy_workqueue() on pg->work_q. > + pg = NULL; > + break; > + } > + if (pg) { > + list_add(&pg->node, &port_group_list); > + h->pg = pg; > + } > spin_unlock(&port_group_lock); > > return SCSI_DH_OK; An explanation in the comments about the ALUA topology and what the device_id vs. the group_id represents might be helpful. It occurred to me that if someone doesn't understand that you can have the same device_id behind different port groups they won't understand this code. HOST ----> STORAGE CTRL PG 1 ----> LUN X ----> ----> LUN X ----> STORAGE CTRL PG 2 ----> LUN X ----> ----> LUN X Reviewed-by: Ewan D. Milne <emilne@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 09/22/2015 09:31 PM, Ewan Milne wrote: > On Thu, 2015-08-27 at 14:41 +0200, Hannes Reinecke wrote: >> Use scsi_vpd_lun_id() to assign a unique device identification >> to the alua port group structure. >> >> Signed-off-by: Hannes Reinecke <hare@suse.de> >> --- >> drivers/scsi/device_handler/scsi_dh_alua.c | 70 +++++++++++++++++++++++++++--- >> 1 file changed, 65 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c >> index dbe9ff2..c2b2100b 100644 >> --- a/drivers/scsi/device_handler/scsi_dh_alua.c >> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c >> @@ -70,6 +70,8 @@ static DEFINE_SPINLOCK(port_group_lock); >> struct alua_port_group { >> struct kref kref; >> struct list_head node; >> + unsigned char device_id_str[256]; >> + int device_id_size; > > I prefer _len instead of _size, _size should refer to the size of the buffer, > not the current length of the data in it. > >> int group_id; >> int tpgs; >> int state; >> @@ -229,7 +231,9 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) >> { >> unsigned char *d; >> int group_id = -1; >> - struct alua_port_group *pg = NULL; >> + char device_id_str[256]; >> + int device_id_size; >> + struct alua_port_group *tmp_pg, *pg = NULL; >> >> if (!sdev->vpd_pg83) >> return SCSI_DH_DEV_UNSUPP; >> @@ -266,9 +270,39 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) >> h->tpgs = TPGS_MODE_NONE; >> return SCSI_DH_DEV_UNSUPP; >> } >> + device_id_size = scsi_vpd_lun_id(sdev, device_id_str, 256); > > should be sizeof(device_id_str) not hardcoded 256 > Okay. >> + if (device_id_size <= 0) { >> + /* >> + * Internal error: TPGS supported by no > > "Internal error: TPGS supported by no" should be "but no" > Fixed now. >> + * device identifcation found. >> + * Disable ALUA support. >> + */ >> + sdev_printk(KERN_INFO, sdev, >> + "%s: No device descriptors found\n", >> + ALUA_DH_NAME); >> + h->tpgs = TPGS_MODE_NONE; >> + return SCSI_DH_DEV_UNSUPP; >> + } >> sdev_printk(KERN_INFO, sdev, >> - "%s: port group %02x rel port %02x\n", >> - ALUA_DH_NAME, group_id, h->rel_port); >> + "%s: device %s port group %02x " >> + "rel port %02x\n", ALUA_DH_NAME, >> + device_id_str, group_id, h->rel_port); >> + spin_lock(&port_group_lock); >> + list_for_each_entry(tmp_pg, &port_group_list, node) { >> + if (tmp_pg->group_id != group_id) >> + continue; >> + if (tmp_pg->device_id_size != device_id_size) >> + continue; >> + if (strncmp(tmp_pg->device_id_str, device_id_str, >> + device_id_size)) >> + continue; >> + h->pg = tmp_pg; >> + kref_get(&tmp_pg->kref); >> + break; >> + } >> + spin_unlock(&port_group_lock); >> + if (h->pg) >> + return SCSI_DH_OK; > > The lookup checks whether h->pg == NULL but the function never > explicitly sets it to NULL before iterating. > For my next iteration I've reworked this so that h->pg is explicitly set. >> >> pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL); >> if (!pg) { >> @@ -278,13 +312,39 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) >> /* Temporary failure, bypass */ >> return SCSI_DH_DEV_TEMP_BUSY; >> } >> + if (device_id_size) >> + strncpy(pg->device_id_str, device_id_str, 256); > > should be sizeof(device_id_str) not hardcoded 256 > Okay. >> + else >> + pg->device_id_str[0] = '\0'; >> + >> + pg->device_id_size = device_id_size; >> pg->group_id = group_id; >> pg->tpgs = h->tpgs; >> pg->state = TPGS_STATE_OPTIMIZED; >> kref_init(&pg->kref); >> spin_lock(&port_group_lock); >> - list_add(&pg->node, &port_group_list); >> - h->pg = pg; >> + /* >> + * Re-check list again to catch >> + * concurrent updates >> + */ >> + list_for_each_entry(tmp_pg, &port_group_list, node) { >> + if (tmp_pg->group_id != pg->group_id) >> + continue; >> + if (tmp_pg->device_id_size != pg->device_id_size) >> + continue; >> + if (strncmp(tmp_pg->device_id_str, pg->device_id_str, >> + device_id_size)) >> + continue; >> + h->pg = tmp_pg; >> + kref_get(&tmp_pg->kref); >> + kfree(pg); > > With the added check for an existing alua_port_group object, and the kfree() of > the alua_port_group that had been allocated if an existing one is found, the code does not > do a destroy_workqueue() on pg->work_q. > With the current rework I've removed the per-pg workqueues, so that issue doesn't occur anymore. >> + pg = NULL; >> + break; >> + } >> + if (pg) { >> + list_add(&pg->node, &port_group_list); >> + h->pg = pg; >> + } >> spin_unlock(&port_group_lock); >> >> return SCSI_DH_OK; > > An explanation in the comments about the ALUA topology and what the device_id vs. > the group_id represents might be helpful. It occurred to me that if someone doesn't > understand that you can have the same device_id behind different port groups they > won't understand this code. > > HOST ----> STORAGE CTRL PG 1 ----> LUN X > ----> ----> LUN X > ----> STORAGE CTRL PG 2 ----> LUN X > ----> ----> LUN X > Hmm. Someone willing to understand this code should be reasonable familiar with SPC, so I doubt that'll be an issue. Cheers, Hannes
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index dbe9ff2..c2b2100b 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -70,6 +70,8 @@ static DEFINE_SPINLOCK(port_group_lock); struct alua_port_group { struct kref kref; struct list_head node; + unsigned char device_id_str[256]; + int device_id_size; int group_id; int tpgs; int state; @@ -229,7 +231,9 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) { unsigned char *d; int group_id = -1; - struct alua_port_group *pg = NULL; + char device_id_str[256]; + int device_id_size; + struct alua_port_group *tmp_pg, *pg = NULL; if (!sdev->vpd_pg83) return SCSI_DH_DEV_UNSUPP; @@ -266,9 +270,39 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) h->tpgs = TPGS_MODE_NONE; return SCSI_DH_DEV_UNSUPP; } + device_id_size = scsi_vpd_lun_id(sdev, device_id_str, 256); + if (device_id_size <= 0) { + /* + * Internal error: TPGS supported by no + * device identifcation found. + * Disable ALUA support. + */ + sdev_printk(KERN_INFO, sdev, + "%s: No device descriptors found\n", + ALUA_DH_NAME); + h->tpgs = TPGS_MODE_NONE; + return SCSI_DH_DEV_UNSUPP; + } sdev_printk(KERN_INFO, sdev, - "%s: port group %02x rel port %02x\n", - ALUA_DH_NAME, group_id, h->rel_port); + "%s: device %s port group %02x " + "rel port %02x\n", ALUA_DH_NAME, + device_id_str, group_id, h->rel_port); + spin_lock(&port_group_lock); + list_for_each_entry(tmp_pg, &port_group_list, node) { + if (tmp_pg->group_id != group_id) + continue; + if (tmp_pg->device_id_size != device_id_size) + continue; + if (strncmp(tmp_pg->device_id_str, device_id_str, + device_id_size)) + continue; + h->pg = tmp_pg; + kref_get(&tmp_pg->kref); + break; + } + spin_unlock(&port_group_lock); + if (h->pg) + return SCSI_DH_OK; pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL); if (!pg) { @@ -278,13 +312,39 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) /* Temporary failure, bypass */ return SCSI_DH_DEV_TEMP_BUSY; } + if (device_id_size) + strncpy(pg->device_id_str, device_id_str, 256); + else + pg->device_id_str[0] = '\0'; + + pg->device_id_size = device_id_size; pg->group_id = group_id; pg->tpgs = h->tpgs; pg->state = TPGS_STATE_OPTIMIZED; kref_init(&pg->kref); spin_lock(&port_group_lock); - list_add(&pg->node, &port_group_list); - h->pg = pg; + /* + * Re-check list again to catch + * concurrent updates + */ + list_for_each_entry(tmp_pg, &port_group_list, node) { + if (tmp_pg->group_id != pg->group_id) + continue; + if (tmp_pg->device_id_size != pg->device_id_size) + continue; + if (strncmp(tmp_pg->device_id_str, pg->device_id_str, + device_id_size)) + continue; + h->pg = tmp_pg; + kref_get(&tmp_pg->kref); + kfree(pg); + pg = NULL; + break; + } + if (pg) { + list_add(&pg->node, &port_group_list); + h->pg = pg; + } spin_unlock(&port_group_lock); return SCSI_DH_OK;
Use scsi_vpd_lun_id() to assign a unique device identification to the alua port group structure. Signed-off-by: Hannes Reinecke <hare@suse.de> --- drivers/scsi/device_handler/scsi_dh_alua.c | 70 +++++++++++++++++++++++++++--- 1 file changed, 65 insertions(+), 5 deletions(-)