[CVE-2017-18232][A][PATCH 07/11] scsi: libsas: make the event threshold configurable

[Khalid Elmously]

From: Jason Yan <yanaijie at huawei.com>

CVE-2017-18232

Add a sysfs attr that LLDD can configure it for every host. We made an
example in hisi_sas. Other LLDDs using libsas can implement it if they
want.

Suggested-by: Hannes Reinecke <hare at suse.com>
Signed-off-by: Jason Yan <yanaijie at huawei.com>
CC: John Garry <john.garry at huawei.com>
CC: Johannes Thumshirn <jthumshirn at suse.de>
CC: Ewan Milne <emilne at redhat.com>
CC: Christoph Hellwig <hch at lst.de>
CC: Tomas Henzl <thenzl at redhat.com>
CC: Dan Williams <dan.j.williams at intel.com>
Acked-by: John Garry <john.garry at huawei.com> #for hisi_sas part
Reviewed-by: Hannes Reinecke <hare at suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
(cherry-picked from 8eea9dd84e450e5262643823691108f2a208a2ac )
Signed-off-by: Khalid Elmously <khalid.elmously at canonical.com>
---
 drivers/scsi/hisi_sas/hisi_sas_main.c |  6 ++++++
 drivers/scsi/libsas/sas_init.c        | 31 +++++++++++++++++++++++++++
 include/scsi/libsas.h                 |  1 +
 3 files changed, 38 insertions(+)

diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 2bdd039a3d51..ce699a76dd4d 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -1554,6 +1554,11 @@ EXPORT_SYMBOL_GPL(hisi_sas_kill_tasklets);
 struct scsi_transport_template *hisi_sas_stt;
 EXPORT_SYMBOL_GPL(hisi_sas_stt);
 
+struct device_attribute *host_attrs[] = {
+	&dev_attr_phy_event_threshold,
+	NULL,
+};
+
 static struct scsi_host_template _hisi_sas_sht = {
 	.module			= THIS_MODULE,
 	.name			= DRV_NAME,
@@ -1573,6 +1578,7 @@ static struct scsi_host_template _hisi_sas_sht = {
 	.eh_bus_reset_handler	= sas_eh_bus_reset_handler,
 	.target_destroy		= sas_target_destroy,
 	.ioctl			= sas_ioctl,
+	.shost_attrs		= host_attrs,
 };
 struct scsi_host_template *hisi_sas_sht = &_hisi_sas_sht;
 EXPORT_SYMBOL_GPL(hisi_sas_sht);
diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 1957716dbcf6..811128eb0283 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -537,6 +537,37 @@ static struct sas_function_template sft = {
 	.smp_handler = sas_smp_handler,
 };
 
+static inline ssize_t phy_event_threshold_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct Scsi_Host *shost = class_to_shost(dev);
+	struct sas_ha_struct *sha = SHOST_TO_SAS_HA(shost);
+
+	return scnprintf(buf, PAGE_SIZE, "%u\n", sha->event_thres);
+}
+
+static inline ssize_t phy_event_threshold_store(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	struct Scsi_Host *shost = class_to_shost(dev);
+	struct sas_ha_struct *sha = SHOST_TO_SAS_HA(shost);
+
+	sha->event_thres = simple_strtol(buf, NULL, 10);
+
+	/* threshold cannot be set too small */
+	if (sha->event_thres < 32)
+		sha->event_thres = 32;
+
+	return count;
+}
+
+DEVICE_ATTR(phy_event_threshold,
+	S_IRUGO|S_IWUSR,
+	phy_event_threshold_show,
+	phy_event_threshold_store);
+EXPORT_SYMBOL_GPL(dev_attr_phy_event_threshold);
+
 struct scsi_transport_template *
 sas_domain_attach_transport(struct sas_domain_function_template *dft)
 {
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index a301569a1a7d..0698768cb383 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -680,6 +680,7 @@ extern int sas_bios_param(struct scsi_device *,
 			  sector_t capacity, int *hsc);
 extern struct scsi_transport_template *
 sas_domain_attach_transport(struct sas_domain_function_template *);
+extern struct device_attribute dev_attr_phy_event_threshold;
 
 int  sas_discover_root_expander(struct domain_device *);
 
-- 
2.17.0