linux-kernel - [PATCH 1/3] staging: greybus: loopback.c: remove unused gb

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Message-Id: <20181005142826.26108-1-linux@rasmusvillemoes.dk>
Date:   Fri,  5 Oct 2018 16:28:24 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     "Bryan O'Donoghue" <pure.logic@...us-software.ie>,
        Johan Hovold <johan@...nel.org>, Alex Elder <elder@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        greybus-dev@...ts.linaro.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] staging: greybus: loopback.c: remove unused gb_loopback::lbid

It's not obvious how the code prevents adding more than 31 elements to
the list and thus invoking undefined behaviour in the 1 << new_lbid
expression, and in practice causing ->lbid values to repeat every 32
elements.

But the definition of struct gb_loopback is local to loopback.c, and the
lbid field is entirely unused outside of this function, so it seems we
can just drop it entirely.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
Since lbid isn't mentioned anywhere else in greybus/, it's hard to
figure out how it was meant to be used. It does seem like entirely
dead (write-only) code.

 drivers/staging/greybus/loopback.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index 42f6f3de967c..7080294f705c 100644
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -97,7 +97,6 @@ struct gb_loopback {
 	u32 timeout_min;
 	u32 timeout_max;
 	u32 outstanding_operations_max;
-	u32 lbid;
 	u64 elapsed_nsecs;
 	u32 apbridge_latency_ts;
 	u32 gbphy_latency_ts;
@@ -1014,16 +1013,9 @@ static int gb_loopback_bus_id_compare(void *priv, struct list_head *lha,
 
 static void gb_loopback_insert_id(struct gb_loopback *gb)
 {
-	struct gb_loopback *gb_list;
-	u32 new_lbid = 0;
-
 	/* perform an insertion sort */
 	list_add_tail(&gb->entry, &gb_dev.list);
 	list_sort(NULL, &gb_dev.list, gb_loopback_bus_id_compare);
-	list_for_each_entry(gb_list, &gb_dev.list, entry) {
-		gb_list->lbid = 1 << new_lbid;
-		new_lbid++;
-	}
 }
 
 #define DEBUGFS_NAMELEN 32
-- 
2.19.0