| Message ID | 1436353788-104911-2-git-send-email-hare@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 08, 2015 at 01:09:44PM +0200, Hannes Reinecke wrote: > +++ b/drivers/scsi/device_handler/scsi_dh_alua.c > @@ -264,8 +264,11 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) > int device_id_size, device_id_type = 0; > struct alua_port_group *tmp_pg, *pg = NULL; > > - if (!sdev->vpd_pg83) > + rcu_read_lock(); > + if (!rcu_dereference(sdev->vpd_pg83)) { > + rcu_read_unlock(); > return SCSI_DH_DEV_UNSUPP; > + } > > /* > * Look for the correct descriptor. > @@ -281,8 +284,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) > */ > memset(device_id_str, 0, 256); > device_id_size = 0; > - d = sdev->vpd_pg83 + 4; > - while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) { > + d = rcu_dereference(sdev->vpd_pg83) + 4; > + while (d < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) { Seem like this code would benefit from a local variable in favor of the repeated rcu_dereference() calls. > @@ -803,7 +803,7 @@ void scsi_attach_vpd(struct scsi_device *sdev) I think this function could use a new name, e.g. scsi_read_vpd_pages? > @@ -563,8 +563,9 @@ static void ses_match_to_enclosure(struct enclosure_device *edev, > if (!sdev->vpd_pg83_len) > return; > > - desc = sdev->vpd_pg83 + 4; > - while (desc < sdev->vpd_pg83 + sdev->vpd_pg83_len) { > + rcu_read_lock(); > + desc = rcu_dereference(sdev->vpd_pg83) + 4; > + while (desc < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) { A local variable or two would help here as well. -- 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 07/24/2015 04:38 PM, Christoph Hellwig wrote: > On Wed, Jul 08, 2015 at 01:09:44PM +0200, Hannes Reinecke wrote: >> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c >> @@ -264,8 +264,11 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) >> int device_id_size, device_id_type = 0; >> struct alua_port_group *tmp_pg, *pg = NULL; >> >> - if (!sdev->vpd_pg83) >> + rcu_read_lock(); >> + if (!rcu_dereference(sdev->vpd_pg83)) { >> + rcu_read_unlock(); >> return SCSI_DH_DEV_UNSUPP; >> + } >> >> /* >> * Look for the correct descriptor. >> @@ -281,8 +284,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) >> */ >> memset(device_id_str, 0, 256); >> device_id_size = 0; >> - d = sdev->vpd_pg83 + 4; >> - while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) { >> + d = rcu_dereference(sdev->vpd_pg83) + 4; >> + while (d < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) { > > Seem like this code would benefit from a local variable in favor of the > repeated rcu_dereference() calls. > Yeah, possibly. After all, the variable isn't expected to change under rcu_read_lock(). >> @@ -803,7 +803,7 @@ void scsi_attach_vpd(struct scsi_device *sdev) > > I think this function could use a new name, e.g. scsi_read_vpd_pages? > >> @@ -563,8 +563,9 @@ static void ses_match_to_enclosure(struct enclosure_device *edev, >> if (!sdev->vpd_pg83_len) >> return; >> >> - desc = sdev->vpd_pg83 + 4; >> - while (desc < sdev->vpd_pg83 + sdev->vpd_pg83_len) { >> + rcu_read_lock(); >> + desc = rcu_dereference(sdev->vpd_pg83) + 4; >> + while (desc < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) { > > A local variable or two would help here as well. > Okay. Cheers, Hannes
On Fri, Jul 24, 2015 at 04:40:42PM +0200, Hannes Reinecke wrote: > Yeah, possibly. After all, the variable isn't expected to change > under rcu_read_lock(). Actually it can and will change, that's the point. But if you use a local variable you keep a single version of it, which won't be freed until after rcu_read_unlock. -- 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 07/24/2015 04:43 PM, Christoph Hellwig wrote: > On Fri, Jul 24, 2015 at 04:40:42PM +0200, Hannes Reinecke wrote: >> Yeah, possibly. After all, the variable isn't expected to change >> under rcu_read_lock(). > > Actually it can and will change, that's the point. But if you use > a local variable you keep a single version of it, which won't be > freed until after rcu_read_unlock. > Yeah, I figured this as well. Will be updating the patch. Cheers, Hannes
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index d077014..e4cabc8 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -264,8 +264,11 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) int device_id_size, device_id_type = 0; struct alua_port_group *tmp_pg, *pg = NULL; - if (!sdev->vpd_pg83) + rcu_read_lock(); + if (!rcu_dereference(sdev->vpd_pg83)) { + rcu_read_unlock(); return SCSI_DH_DEV_UNSUPP; + } /* * Look for the correct descriptor. @@ -281,8 +284,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) */ memset(device_id_str, 0, 256); device_id_size = 0; - d = sdev->vpd_pg83 + 4; - while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) { + d = rcu_dereference(sdev->vpd_pg83) + 4; + while (d < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) { switch (d[1] & 0xf) { case 0x2: /* EUI-64 */ @@ -366,7 +369,7 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h) } d += d[3] + 4; } - + rcu_read_unlock(); if (group_id == -1) { /* * Internal error; TPGS supported but required diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index 207d6a7..f1c0fb5 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -803,7 +803,7 @@ void scsi_attach_vpd(struct scsi_device *sdev) int vpd_len = SCSI_VPD_PG_LEN; int pg80_supported = 0; int pg83_supported = 0; - unsigned char *vpd_buf; + unsigned char *vpd_buf, *orig_vpd_buf = NULL; if (sdev->skip_vpd_pages) return; @@ -849,8 +849,16 @@ retry_pg80: kfree(vpd_buf); goto retry_pg80; } + mutex_lock(&sdev->inquiry_mutex); + orig_vpd_buf = sdev->vpd_pg80; sdev->vpd_pg80_len = result; - sdev->vpd_pg80 = vpd_buf; + rcu_assign_pointer(sdev->vpd_pg80, vpd_buf); + mutex_unlock(&sdev->inquiry_mutex); + synchronize_rcu(); + if (orig_vpd_buf) { + kfree(orig_vpd_buf); + orig_vpd_buf = NULL; + } vpd_len = SCSI_VPD_PG_LEN; } @@ -870,8 +878,14 @@ retry_pg83: kfree(vpd_buf); goto retry_pg83; } + mutex_lock(&sdev->inquiry_mutex); + orig_vpd_buf = sdev->vpd_pg83; sdev->vpd_pg83_len = result; - sdev->vpd_pg83 = vpd_buf; + rcu_assign_pointer(sdev->vpd_pg83, vpd_buf); + mutex_unlock(&sdev->inquiry_mutex); + synchronize_rcu(); + if (orig_vpd_buf) + kfree(orig_vpd_buf); } } diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index f9f3f82..190d743 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -235,6 +235,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget, INIT_LIST_HEAD(&sdev->starved_entry); INIT_LIST_HEAD(&sdev->event_list); spin_lock_init(&sdev->list_lock); + mutex_init(&sdev->inquiry_mutex); INIT_WORK(&sdev->event_work, scsi_evt_thread); INIT_WORK(&sdev->requeue_work, scsi_requeue_run_queue); @@ -1516,6 +1517,9 @@ EXPORT_SYMBOL(scsi_add_device); void scsi_rescan_device(struct device *dev) { device_lock(dev); + + scsi_attach_vpd(to_scsi_device(dev)); + if (dev->driver && try_module_get(dev->driver->owner)) { struct scsi_driver *drv = to_scsi_driver(dev->driver); diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index e3c3b86..b4de776 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -759,11 +759,15 @@ show_vpd_##_page(struct file *filp, struct kobject *kobj, \ { \ struct device *dev = container_of(kobj, struct device, kobj); \ struct scsi_device *sdev = to_scsi_device(dev); \ + int ret; \ if (!sdev->vpd_##_page) \ return -EINVAL; \ - return memory_read_from_buffer(buf, count, &off, \ - sdev->vpd_##_page, \ + rcu_read_lock(); \ + ret = memory_read_from_buffer(buf, count, &off, \ + rcu_dereference(sdev->vpd_##_page), \ sdev->vpd_##_page##_len); \ + rcu_read_unlock(); \ + return ret; \ } \ static struct bin_attribute dev_attr_vpd_##_page = { \ .attr = {.name = __stringify(vpd_##_page), .mode = S_IRUGO }, \ diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c index dcb0d76..1fc372e 100644 --- a/drivers/scsi/ses.c +++ b/drivers/scsi/ses.c @@ -563,8 +563,9 @@ static void ses_match_to_enclosure(struct enclosure_device *edev, if (!sdev->vpd_pg83_len) return; - desc = sdev->vpd_pg83 + 4; - while (desc < sdev->vpd_pg83 + sdev->vpd_pg83_len) { + rcu_read_lock(); + desc = rcu_dereference(sdev->vpd_pg83) + 4; + while (desc < rcu_dereference(sdev->vpd_pg83) + sdev->vpd_pg83_len) { enum scsi_protocol proto = desc[0] >> 4; u8 code_set = desc[0] & 0x0f; u8 piv = desc[1] & 0x80; @@ -578,6 +579,7 @@ static void ses_match_to_enclosure(struct enclosure_device *edev, desc += len + 4; } + rcu_read_unlock(); if (efd.addr) { efd.dev = &sdev->sdev_gendev; diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 2725f8f..d2f8b7a 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -109,6 +109,7 @@ struct scsi_device { char type; char scsi_level; char inq_periph_qual; /* PQ from INQUIRY data */ + struct mutex inquiry_mutex; unsigned char inquiry_len; /* valid bytes in 'inquiry' */ unsigned char * inquiry; /* INQUIRY response data */ const char * vendor; /* [back_compat] point into 'inquiry' ... */
This patch implements a VPD page rescan if the 'rescan' sysfs attribute is triggered. Signed-off-by: Hannes Reinecke <hare@suse.de> --- drivers/scsi/device_handler/scsi_dh_alua.c | 11 +++++++---- drivers/scsi/scsi.c | 20 +++++++++++++++++--- drivers/scsi/scsi_scan.c | 4 ++++ drivers/scsi/scsi_sysfs.c | 8 ++++++-- drivers/scsi/ses.c | 6 ++++-- include/scsi/scsi_device.h | 1 + 6 files changed, 39 insertions(+), 11 deletions(-)