[SRU][Zesty][Artful][Bionic][PATCH 3/3] scsi: cxlflash: Derive pid through accessors

[Joseph Salisbury]

From: "Matthew R. Ochs" <mrochs at linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1730515

The cxlflash driver tracks process IDs alongside contexts to validate
context ownership. Currently, the process IDs are derived by directly
accessing values from the 'current' task pointer. While this method of
access is fine for the current process, it is incorrect when the parent
process ID is needed as the access requires serialization.

To address the incorrect issue and provide a consistent means of
deriving the process ID within the cxlflash driver, use the task
accessors defined linux/sched.h.

Signed-off-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>
Signed-off-by: Uma Krishnan <ukrishn at linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
(cherry picked from commit d84c198f43c50c6c0bd57571acbf0f000165bd56)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 drivers/scsi/cxlflash/superpipe.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
index f6dc659..1b77fbd 100644
--- a/drivers/scsi/cxlflash/superpipe.c
+++ b/drivers/scsi/cxlflash/superpipe.c
@@ -165,7 +165,7 @@ struct ctx_info *get_context(struct cxlflash_cfg *cfg, u64 rctxid,
 	struct llun_info *lli = arg;
 	u64 ctxid = DECODE_CTXID(rctxid);
 	int rc;
-	pid_t pid = current->tgid, ctxpid = 0;
+	pid_t pid = task_tgid_nr(current), ctxpid = 0;
 
 	if (ctx_ctrl & CTX_CTRL_FILE) {
 		lli = NULL;
@@ -173,7 +173,7 @@ struct ctx_info *get_context(struct cxlflash_cfg *cfg, u64 rctxid,
 	}
 
 	if (ctx_ctrl & CTX_CTRL_CLONE)
-		pid = current->parent->tgid;
+		pid = task_ppid_nr(current);
 
 	if (likely(ctxid < MAX_CONTEXT)) {
 		while (true) {
@@ -826,7 +826,7 @@ static void init_context(struct ctx_info *ctxi, struct cxlflash_cfg *cfg,
 	ctxi->rht_perms = perms;
 	ctxi->ctrl_map = &afu->afu_map->ctrls[ctxid].ctrl;
 	ctxi->ctxid = ENCODE_CTXID(ctxi, ctxid);
-	ctxi->pid = current->tgid; /* tgid = pid */
+	ctxi->pid = task_tgid_nr(current); /* tgid = pid */
 	ctxi->ctx = ctx;
 	ctxi->cfg = cfg;
 	ctxi->file = file;
-- 
2.7.4