scsi: cxlflash: Derive pid through accessors

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: NMatthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: NUma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

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) {
@@ -824,7 +824,7 @@ 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;