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From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: "Bryan O'Donoghue" <pure.logic@nexus-software.ie>,
	Johan Hovold <johan@kernel.org>, Alex Elder <elder@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	greybus-dev@lists.linaro.org, devel@driverdev.osuosl.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 1/3] staging: greybus: loopback.c: remove unused gb_loopback::lbid
Date: Fri,  5 Oct 2018 16:28:24 +0200	[thread overview]
Message-ID: <20181005142826.26108-1-linux@rasmusvillemoes.dk> (raw)

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@rasmusvillemoes.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


             reply	other threads:[~2018-10-05 14:28 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-05 14:28 Rasmus Villemoes [this message]
2018-10-05 14:28 ` [PATCH 2/3] staging: greybus: loopback.c: do insertion in O(n) instead of O(n lg n) Rasmus Villemoes
2018-10-10 23:03   ` Bryan O'Donoghue
2018-10-11 10:11     ` Rasmus Villemoes
2018-10-23 16:20     ` Rasmus Villemoes
2018-10-23 22:30       ` Bryan O'Donoghue
2018-10-05 14:28 ` [PATCH 3/3] staging: greybus: loopback.c: simplify prototype of gb_loopback_bus_id_compare Rasmus Villemoes
2018-10-10 22:57 ` [PATCH 1/3] staging: greybus: loopback.c: remove unused gb_loopback::lbid Bryan O'Donoghue
2018-10-24 10:48 ` [PATCH v2] staging: greybus: loopback.c: remove unused lists Rasmus Villemoes

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