linux-rdma.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH] net/mlx5: reduce stack usage in FW tracer
@ 2019-09-06 15:11 Arnd Bergmann
  2019-09-09 19:39 ` Saeed Mahameed
  0 siblings, 1 reply; 7+ messages in thread
From: Arnd Bergmann @ 2019-09-06 15:11 UTC (permalink / raw)
  To: Saeed Mahameed, Leon Romanovsky, David S. Miller
  Cc: Arnd Bergmann, Feras Daoud, Erez Shitrit, Moshe Shemesh,
	Eran Ben Elisha, Qian Cai, netdev, linux-rdma, linux-kernel

It's generally not ok to put a 512 byte buffer on the stack, as kernel
stack is a scarce resource:

drivers/net/ethernet/mellanox/mlx5/core/diag/fw_tracer.c:660:13: error: stack frame size of 1032 bytes in function 'mlx5_fw_tracer_handle_traces' [-Werror,-Wframe-larger-than=]

This is done in a context that is allowed to sleep, so using
dynamic allocation is ok as well. I'm not too worried about
runtime overhead, as this already contains an snprintf() and
other expensive functions.

Fixes: 70dd6fdb8987 ("net/mlx5: FW tracer, parse traces and kernel tracing support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 .../mellanox/mlx5/core/diag/fw_tracer.c       | 21 ++++++++++---------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/diag/fw_tracer.c b/drivers/net/ethernet/mellanox/mlx5/core/diag/fw_tracer.c
index 2011eaf15cc5..d81e78060f9f 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/diag/fw_tracer.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/diag/fw_tracer.c
@@ -557,16 +557,16 @@ static void mlx5_tracer_print_trace(struct tracer_string_format *str_frmt,
 				    struct mlx5_core_dev *dev,
 				    u64 trace_timestamp)
 {
-	char	tmp[512];
-
-	snprintf(tmp, sizeof(tmp), str_frmt->string,
-		 str_frmt->params[0],
-		 str_frmt->params[1],
-		 str_frmt->params[2],
-		 str_frmt->params[3],
-		 str_frmt->params[4],
-		 str_frmt->params[5],
-		 str_frmt->params[6]);
+	char *tmp = kasprintf(GFP_KERNEL, str_frmt->string,
+			      str_frmt->params[0],
+			      str_frmt->params[1],
+			      str_frmt->params[2],
+			      str_frmt->params[3],
+			      str_frmt->params[4],
+			      str_frmt->params[5],
+			      str_frmt->params[6]);
+	if (!tmp)
+		return;
 
 	trace_mlx5_fw(dev->tracer, trace_timestamp, str_frmt->lost,
 		      str_frmt->event_id, tmp);
@@ -576,6 +576,7 @@ static void mlx5_tracer_print_trace(struct tracer_string_format *str_frmt,
 
 	/* remove it from hash */
 	mlx5_tracer_clean_message(str_frmt);
+	kfree(tmp);
 }
 
 static int mlx5_tracer_handle_string_trace(struct mlx5_fw_tracer *tracer,
-- 
2.20.0


^ permalink raw reply related	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2019-09-10 19:13 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-06 15:11 [PATCH] net/mlx5: reduce stack usage in FW tracer Arnd Bergmann
2019-09-09 19:39 ` Saeed Mahameed
2019-09-09 20:18   ` Arnd Bergmann
2019-09-09 21:53     ` Saeed Mahameed
2019-09-10  8:14       ` Arnd Bergmann
2019-09-10 15:38         ` David Laight
2019-09-10 19:13           ` Saeed Mahameed

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).