Patch "tracing/net_sched: Fix tracepoints that save qdisc_dev() as a string" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tracing/net_sched: Fix tracepoints that save qdisc_dev() as a string

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-net_sched-fix-tracepoints-that-save-qdisc_de.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9d17fa3f851080ae66e13a2960ef3bbb267e664f
Author: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Date:   Thu Feb 29 14:34:44 2024 -0500

    tracing/net_sched: Fix tracepoints that save qdisc_dev() as a string
    
    [ Upstream commit 51270d573a8d9dd5afdc7934de97d66c0e14b5fd ]
    
    I'm updating __assign_str() and will be removing the second parameter. To
    make sure that it does not break anything, I make sure that it matches the
    __string() field, as that is where the string is actually going to be
    saved in. To make sure there's nothing that breaks, I added a WARN_ON() to
    make sure that what was used in __string() is the same that is used in
    __assign_str().
    
    In doing this change, an error was triggered as __assign_str() now expects
    the string passed in to be a char * value. I instead had the following
    warning:
    
    include/trace/events/qdisc.h: In function ‘trace_event_raw_event_qdisc_reset’:
    include/trace/events/qdisc.h:91:35: error: passing argument 1 of 'strcmp' from incompatible pointer type [-Werror=incompatible-pointer-types]
       91 |                 __assign_str(dev, qdisc_dev(q));
    
    That's because the qdisc_enqueue() and qdisc_reset() pass in qdisc_dev(q)
    to __assign_str() and to __string(). But that function returns a pointer
    to struct net_device and not a string.
    
    It appears that these events are just saving the pointer as a string and
    then reading it as a string as well.
    
    Use qdisc_dev(q)->name to save the device instead.
    
    Fixes: a34dac0b90552 ("net_sched: add tracepoints for qdisc_reset() and qdisc_destroy()")
    Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
    Reviewed-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h
index 59c945b66f9c7..5180da19d837f 100644
--- a/include/trace/events/qdisc.h
+++ b/include/trace/events/qdisc.h
@@ -81,14 +81,14 @@ TRACE_EVENT(qdisc_reset,
 	TP_ARGS(q),
 
 	TP_STRUCT__entry(
-		__string(	dev,		qdisc_dev(q)	)
-		__string(	kind,		q->ops->id	)
-		__field(	u32,		parent		)
-		__field(	u32,		handle		)
+		__string(	dev,		qdisc_dev(q)->name	)
+		__string(	kind,		q->ops->id		)
+		__field(	u32,		parent			)
+		__field(	u32,		handle			)
 	),
 
 	TP_fast_assign(
-		__assign_str(dev, qdisc_dev(q));
+		__assign_str(dev, qdisc_dev(q)->name);
 		__assign_str(kind, q->ops->id);
 		__entry->parent = q->parent;
 		__entry->handle = q->handle;
@@ -106,14 +106,14 @@ TRACE_EVENT(qdisc_destroy,
 	TP_ARGS(q),
 
 	TP_STRUCT__entry(
-		__string(	dev,		qdisc_dev(q)	)
-		__string(	kind,		q->ops->id	)
-		__field(	u32,		parent		)
-		__field(	u32,		handle		)
+		__string(	dev,		qdisc_dev(q)->name	)
+		__string(	kind,		q->ops->id		)
+		__field(	u32,		parent			)
+		__field(	u32,		handle			)
 	),
 
 	TP_fast_assign(
-		__assign_str(dev, qdisc_dev(q));
+		__assign_str(dev, qdisc_dev(q)->name);
 		__assign_str(kind, q->ops->id);
 		__entry->parent = q->parent;
 		__entry->handle = q->handle;