In non-coherent DMA mode, kernel uses cache flushing operations to
maintain I/O coherency, so libsas's SMP request/response should be
aligned to ARCH_DMA_MINALIGN. Otherwise, If a DMA buffer and a kernel
structure share a same cache line, and if the kernel structure has
dirty data, cache_invalidate (no writeback) will cause data corruption.

Cc: sta...@vger.kernel.org
Signed-off-by: Huacai Chen <che...@lemote.com>
---
 drivers/scsi/libsas/sas_expander.c | 93 +++++++++++++++++++++++---------------
 1 file changed, 57 insertions(+), 36 deletions(-)

diff --git a/drivers/scsi/libsas/sas_expander.c 
b/drivers/scsi/libsas/sas_expander.c
index 6b4fd23..124a44b 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -164,17 +164,17 @@ static int smp_execute_task(struct domain_device *dev, 
void *req, int req_size,
 
 /* ---------- Allocations ---------- */
 
-static inline void *alloc_smp_req(int size)
+static inline void *alloc_smp_req(int size, int align)
 {
-       u8 *p = kzalloc(size, GFP_KERNEL);
+       u8 *p = kzalloc(ALIGN(size, align), GFP_KERNEL);
        if (p)
                p[0] = SMP_REQUEST;
        return p;
 }
 
-static inline void *alloc_smp_resp(int size)
+static inline void *alloc_smp_resp(int size, int align)
 {
-       return kzalloc(size, GFP_KERNEL);
+       return kzalloc(ALIGN(size, align), GFP_KERNEL);
 }
 
 static char sas_route_char(struct domain_device *dev, struct ex_phy *phy)
@@ -403,15 +403,17 @@ static int sas_ex_phy_discover_helper(struct 
domain_device *dev, u8 *disc_req,
 int sas_ex_phy_discover(struct domain_device *dev, int single)
 {
        struct expander_device *ex = &dev->ex_dev;
-       int  res = 0;
+       int  res = 0, align;
        u8   *disc_req;
        u8   *disc_resp;
 
-       disc_req = alloc_smp_req(DISCOVER_REQ_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       disc_req = alloc_smp_req(DISCOVER_REQ_SIZE, align);
        if (!disc_req)
                return -ENOMEM;
 
-       disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE);
+       disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE, align);
        if (!disc_resp) {
                kfree(disc_req);
                return -ENOMEM;
@@ -480,14 +482,15 @@ static int sas_ex_general(struct domain_device *dev)
 {
        u8 *rg_req;
        struct smp_resp *rg_resp;
-       int res;
-       int i;
+       int i, res, align;
 
-       rg_req = alloc_smp_req(RG_REQ_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       rg_req = alloc_smp_req(RG_REQ_SIZE, align);
        if (!rg_req)
                return -ENOMEM;
 
-       rg_resp = alloc_smp_resp(RG_RESP_SIZE);
+       rg_resp = alloc_smp_resp(RG_RESP_SIZE, align);
        if (!rg_resp) {
                kfree(rg_req);
                return -ENOMEM;
@@ -552,13 +555,15 @@ static int sas_ex_manuf_info(struct domain_device *dev)
 {
        u8 *mi_req;
        u8 *mi_resp;
-       int res;
+       int res, align;
 
-       mi_req = alloc_smp_req(MI_REQ_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       mi_req = alloc_smp_req(MI_REQ_SIZE, align);
        if (!mi_req)
                return -ENOMEM;
 
-       mi_resp = alloc_smp_resp(MI_RESP_SIZE);
+       mi_resp = alloc_smp_resp(MI_RESP_SIZE, align);
        if (!mi_resp) {
                kfree(mi_req);
                return -ENOMEM;
@@ -593,13 +598,15 @@ int sas_smp_phy_control(struct domain_device *dev, int 
phy_id,
 {
        u8 *pc_req;
        u8 *pc_resp;
-       int res;
+       int res, align;
+
+       align = dma_get_cache_alignment(&dev->phy->dev);
 
-       pc_req = alloc_smp_req(PC_REQ_SIZE);
+       pc_req = alloc_smp_req(PC_REQ_SIZE, align);
        if (!pc_req)
                return -ENOMEM;
 
-       pc_resp = alloc_smp_resp(PC_RESP_SIZE);
+       pc_resp = alloc_smp_resp(PC_RESP_SIZE, align);
        if (!pc_resp) {
                kfree(pc_req);
                return -ENOMEM;
@@ -664,17 +671,19 @@ static int sas_dev_present_in_domain(struct asd_sas_port 
*port,
 #define RPEL_RESP_SIZE 32
 int sas_smp_get_phy_events(struct sas_phy *phy)
 {
-       int res;
+       int res, align;
        u8 *req;
        u8 *resp;
        struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent);
        struct domain_device *dev = sas_find_dev_by_rphy(rphy);
 
-       req = alloc_smp_req(RPEL_REQ_SIZE);
+       align = dma_get_cache_alignment(&phy->dev);
+
+       req = alloc_smp_req(RPEL_REQ_SIZE, align);
        if (!req)
                return -ENOMEM;
 
-       resp = alloc_smp_resp(RPEL_RESP_SIZE);
+       resp = alloc_smp_resp(RPEL_RESP_SIZE, align);
        if (!resp) {
                kfree(req);
                return -ENOMEM;
@@ -709,7 +718,8 @@ int sas_get_report_phy_sata(struct domain_device *dev, int 
phy_id,
                            struct smp_resp *rps_resp)
 {
        int res;
-       u8 *rps_req = alloc_smp_req(RPS_REQ_SIZE);
+       int align = dma_get_cache_alignment(&dev->phy->dev);
+       u8 *rps_req = alloc_smp_req(RPS_REQ_SIZE, align);
        u8 *resp = (u8 *)rps_resp;
 
        if (!rps_req)
@@ -1398,7 +1408,7 @@ static int sas_check_parent_topology(struct domain_device 
*child)
 static int sas_configure_present(struct domain_device *dev, int phy_id,
                                 u8 *sas_addr, int *index, int *present)
 {
-       int i, res = 0;
+       int i, res = 0, align;
        struct expander_device *ex = &dev->ex_dev;
        struct ex_phy *phy = &ex->ex_phy[phy_id];
        u8 *rri_req;
@@ -1406,12 +1416,13 @@ static int sas_configure_present(struct domain_device 
*dev, int phy_id,
 
        *present = 0;
        *index = 0;
+       align = dma_get_cache_alignment(&dev->phy->dev);
 
-       rri_req = alloc_smp_req(RRI_REQ_SIZE);
+       rri_req = alloc_smp_req(RRI_REQ_SIZE, align);
        if (!rri_req)
                return -ENOMEM;
 
-       rri_resp = alloc_smp_resp(RRI_RESP_SIZE);
+       rri_resp = alloc_smp_resp(RRI_RESP_SIZE, align);
        if (!rri_resp) {
                kfree(rri_req);
                return -ENOMEM;
@@ -1472,15 +1483,17 @@ static int sas_configure_present(struct domain_device 
*dev, int phy_id,
 static int sas_configure_set(struct domain_device *dev, int phy_id,
                             u8 *sas_addr, int index, int include)
 {
-       int res;
+       int res, align;
        u8 *cri_req;
        u8 *cri_resp;
 
-       cri_req = alloc_smp_req(CRI_REQ_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       cri_req = alloc_smp_req(CRI_REQ_SIZE, align);
        if (!cri_req)
                return -ENOMEM;
 
-       cri_resp = alloc_smp_resp(CRI_RESP_SIZE);
+       cri_resp = alloc_smp_resp(CRI_RESP_SIZE, align);
        if (!cri_resp) {
                kfree(cri_req);
                return -ENOMEM;
@@ -1689,10 +1702,12 @@ int sas_discover_root_expander(struct domain_device 
*dev)
 static int sas_get_phy_discover(struct domain_device *dev,
                                int phy_id, struct smp_resp *disc_resp)
 {
-       int res;
+       int res, align;
        u8 *disc_req;
 
-       disc_req = alloc_smp_req(DISCOVER_REQ_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       disc_req = alloc_smp_req(DISCOVER_REQ_SIZE, align);
        if (!disc_req)
                return -ENOMEM;
 
@@ -1715,10 +1730,12 @@ static int sas_get_phy_discover(struct domain_device 
*dev,
 static int sas_get_phy_change_count(struct domain_device *dev,
                                    int phy_id, int *pcc)
 {
-       int res;
+       int res, align;
        struct smp_resp *disc_resp;
 
-       disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE, align);
        if (!disc_resp)
                return -ENOMEM;
 
@@ -1733,11 +1750,13 @@ static int sas_get_phy_change_count(struct 
domain_device *dev,
 static int sas_get_phy_attached_dev(struct domain_device *dev, int phy_id,
                                    u8 *sas_addr, enum sas_device_type *type)
 {
-       int res;
+       int res, align;
        struct smp_resp *disc_resp;
        struct discover_resp *dr;
 
-       disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       disc_resp = alloc_smp_resp(DISCOVER_RESP_SIZE, align);
        if (!disc_resp)
                return -ENOMEM;
        dr = &disc_resp->disc;
@@ -1787,15 +1806,17 @@ static int sas_find_bcast_phy(struct domain_device 
*dev, int *phy_id,
 
 static int sas_get_ex_change_count(struct domain_device *dev, int *ecc)
 {
-       int res;
+       int res, align;
        u8  *rg_req;
        struct smp_resp  *rg_resp;
 
-       rg_req = alloc_smp_req(RG_REQ_SIZE);
+       align = dma_get_cache_alignment(&dev->phy->dev);
+
+       rg_req = alloc_smp_req(RG_REQ_SIZE, align);
        if (!rg_req)
                return -ENOMEM;
 
-       rg_resp = alloc_smp_resp(RG_RESP_SIZE);
+       rg_resp = alloc_smp_resp(RG_RESP_SIZE, align);
        if (!rg_resp) {
                kfree(rg_req);
                return -ENOMEM;
-- 
2.7.0



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