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(fsb6a9315e.tkyc502.ap.nuro.jp. [182.169.49.94]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a88b413d16sm135081995ad.25.2026.02.01.18.45.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Feb 2026 18:45:41 -0800 (PST) From: Keita Morisaki To: Peter Wang , Chaotian Jing Cc: Stanley Jhu , "James E . J . Bottomley" , "Martin K . Petersen" , linux-scsi@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, Keita Morisaki Subject: [PATCH] scsi: ufs: mediatek: Fix page faults in ufs_mtk_clk_scale trace event Date: Mon, 2 Feb 2026 11:45:26 +0900 Message-Id: <20260202024526.122515-1-keita.morisaki@tier4.jp> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The ufs_mtk_clk_scale trace event currently stores the address of the name string directly via __field(const char *, name). This pointer may become invalid after the module is unloaded, causing page faults when the trace buffer is subsequently accessed. This can occur because the MediaTek UFS driver can be configured as a loadable module (tristate in Kconfig), meaning the name string passed to the trace event may reside in module memory that becomes invalid after module unload. Fix this by using __string() and __assign_str() to copy the string contents into the ring buffer instead of storing the pointer. This ensures the trace data remains valid regardless of module state. This change increases the memory usage for each ftrace entry by a few bytes (clock names are typically 7-15 characters like "ufs_sel" or "ufs_sel_max_src") compared to storing an 8-byte pointer. Note that this change does not affect anything unless all of the following conditions are met: - CONFIG_SCSI_UFS_MEDIATEK is enabled - ftrace tracing is enabled - The ufs_mtk_clk_scale event is enabled in ftrace Signed-off-by: Keita Morisaki Reviewed-by: Peter Wang --- drivers/ufs/host/ufs-mediatek-trace.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/ufs/host/ufs-mediatek-trace.h b/drivers/ufs/host/ufs-m= ediatek-trace.h index b5f2ec314..0df8ac843 100644 --- a/drivers/ufs/host/ufs-mediatek-trace.h +++ b/drivers/ufs/host/ufs-mediatek-trace.h @@ -33,19 +33,19 @@ TRACE_EVENT(ufs_mtk_clk_scale, TP_ARGS(name, scale_up, clk_rate), =20 TP_STRUCT__entry( - __field(const char*, name) + __string(name, name) __field(bool, scale_up) __field(unsigned long, clk_rate) ), =20 TP_fast_assign( - __entry->name =3D name; + __assign_str(name); __entry->scale_up =3D scale_up; __entry->clk_rate =3D clk_rate; ), =20 TP_printk("ufs: clk (%s) scaled %s @ %lu", - __entry->name, + __get_str(name), __entry->scale_up ? "up" : "down", __entry->clk_rate) ); base-commit: 18f7fcd5e69a04df57b563360b88be72471d6b62 --=20 2.34.1