linux-kernel - [PATCH v2] coresight: trbe: Return NULL pointer for allocation failures

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Message-Id: <20250904-cs_etm_auxsetup_fix_error_handling-v2-1-a502d0bafb95@arm.com>
Date: Thu, 04 Sep 2025 15:13:52 +0100
From: Leo Yan <leo.yan@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>, 
 Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>, 
 Anshuman Khandual <anshuman.khandual@....com>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Tamas Zsoldos <tamas.zsoldos@....com>, 
 Leo Yan <leo.yan@....com>
Subject: [PATCH v2] coresight: trbe: Return NULL pointer for allocation
 failures

When the TRBE driver fails to allocate a buffer, it currently returns
the error code "-ENOMEM". However, the caller etm_setup_aux() only
checks for a NULL pointer, so it misses the error. As a result, the
driver continues and eventually causes a kernel panic.

Fix this by returning a NULL pointer from arm_trbe_alloc_buffer() on
allocation failures. This allows that the callers can properly handle
the failure.

Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
Reported-by: Tamas Zsoldos <tamas.zsoldos@....com>
Signed-off-by: Leo Yan <leo.yan@....com>
---
Changes in v2:
- Fix TRBE driver instead of changing coresight-etm-perf.c.
- Link to v1: https://lore.kernel.org/r/20250904-cs_etm_auxsetup_fix_error_handling-v1-1-ecc5edf282a5@arm.com
---
 drivers/hwtracing/coresight/coresight-trbe.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 10f3fb401edf6a00b24b38cdaa7c2865e7a191ac..8f9bbef71f236b327d35a288689df9b0dd8ff3f4 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -748,12 +748,12 @@ static void *arm_trbe_alloc_buffer(struct coresight_device *csdev,
 
 	buf = kzalloc_node(sizeof(*buf), GFP_KERNEL, trbe_alloc_node(event));
 	if (!buf)
-		return ERR_PTR(-ENOMEM);
+		return NULL;
 
 	pglist = kcalloc(nr_pages, sizeof(*pglist), GFP_KERNEL);
 	if (!pglist) {
 		kfree(buf);
-		return ERR_PTR(-ENOMEM);
+		return NULL;
 	}
 
 	for (i = 0; i < nr_pages; i++)
@@ -763,7 +763,7 @@ static void *arm_trbe_alloc_buffer(struct coresight_device *csdev,
 	if (!buf->trbe_base) {
 		kfree(pglist);
 		kfree(buf);
-		return ERR_PTR(-ENOMEM);
+		return NULL;
 	}
 	buf->trbe_limit = buf->trbe_base + nr_pages * PAGE_SIZE;
 	buf->trbe_write = buf->trbe_base;

---
base-commit: fa71e9cb4cfa59abb196229667ec84929bdc18fe
change-id: 20250904-cs_etm_auxsetup_fix_error_handling-cb7e07ed9adf

Best regards,
-- 
Leo Yan <leo.yan@....com>