From:   Arnd Bergmann <arnd@kernel.org>
To:     Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
        Vinod Koul <vkoul@kernel.org>,
        Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc:     Arnd Bergmann <arnd@arndb.de>, Bjorn Helgaas <bhelgaas@google.com>,
        Manivannan Sadhasivam <mani@kernel.org>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Frank Li <Frank.Li@nxp.com>, dmaengine@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] dmaengine: dw-edma: reduce stack usage after debugfs rework
Date:   Mon, 30 Jan 2023 14:08:10 +0100
Message-Id: <20230130130826.596171-1-arnd@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Arnd Bergmann <arnd@arndb.de>

After the dw_edma_debugfs_entry arrays are no longer compile-time
constant, they take up space on the stack, which exceeds the
warning limit after inlining:

drivers/dma/dw-edma/dw-edma-v0-debugfs.c:280:6: error: stack frame size (1784) exceeds limit (1400) in 'dw_edma_v0_debugfs_on' [-Werror,-Wframe-larger-than]
void dw_edma_v0_debugfs_on(struct dw_edma *dw)

Work around this by marking the functions with the largest arrays
as 'noinline_for_stack' to make them not use up space on the same
stack together.

Fixes: 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
index 7be23c26ac88..9dfcbbdfb27b 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-debugfs.c
@@ -116,7 +116,8 @@ static void dw_edma_debugfs_create_x32(struct dw_edma *dw,
 	}
 }
 
-static void dw_edma_debugfs_regs_ch(struct dw_edma *dw, enum dw_edma_dir dir,
+static noinline_for_stack void
+dw_edma_debugfs_regs_ch(struct dw_edma *dw, enum dw_edma_dir dir,
 				    u16 ch, struct dentry *dent)
 {
 	struct dw_edma_debugfs_entry debugfs_regs[] = {
@@ -136,9 +137,10 @@ static void dw_edma_debugfs_regs_ch(struct dw_edma *dw, enum dw_edma_dir dir,
 	dw_edma_debugfs_create_x32(dw, debugfs_regs, nr_entries, dent);
 }
 
-static void dw_edma_debugfs_regs_wr(struct dw_edma *dw, struct dentry *dent)
+static noinline_for_stack void
+dw_edma_debugfs_regs_wr(struct dw_edma *dw, struct dentry *dent)
 {
-	static const struct dw_edma_debugfs_entry debugfs_regs[] = {
+	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */
 		WR_REGISTER(dw, engine_en),
 		WR_REGISTER(dw, doorbell),
@@ -159,7 +161,7 @@ static void dw_edma_debugfs_regs_wr(struct dw_edma *dw, struct dentry *dent)
 		WR_REGISTER(dw, ch67_imwr_data),
 		WR_REGISTER(dw, linked_list_err_en),
 	};
-	static const struct dw_edma_debugfs_entry debugfs_unroll_regs[] = {
+	const struct dw_edma_debugfs_entry debugfs_unroll_regs[] = {
 		/* eDMA channel context grouping */
 		WR_REGISTER_UNROLL(dw, engine_chgroup),
 		WR_REGISTER_UNROLL(dw, engine_hshake_cnt.lsb),
@@ -197,7 +199,8 @@ static void dw_edma_debugfs_regs_wr(struct dw_edma *dw, struct dentry *dent)
 	}
 }
 
-static void dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
+static noinline void
+dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */
-- 
2.39.0