dmaengine: dw-edma: reduce stack usage after debugfs rework

PATCH In review Arnd Bergmann 5 participants 8 messages Jan 30, 2023 – Feb 12, 2023

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Arnd Bergmann

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2023-01-30 18:51 UTC #0 lore raw

PATCH v2 1/1 dmaengine: dw-edma: reduce stack usage after debugfs rework

From: Arnd Bergmann <[email protected]>

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 preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.

Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")

Signed-off-by Arnd Bergmann <[email protected]>

---
v2: rebase on top of dmaengine tree

---
 drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

drivers/dma/dw-edma/dw-edma-v0-debugfs.c +4 -2

index 42380bf64a70..6542060bd01a 100644
@@ -136,7 +136,8 @@ 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)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

@@ -197,7 +198,8 @@ 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_for_stack void
+dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

Signature · 1 line

2.39.0

Manivannan Sadhasivam

maintainer Reviewed-by on v2 1/1

2023-01-31 06:45 UTC #1 lore raw

Quoted 3 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>
After the dw_edma_debugfs_entry arrays are no longer compile-time

This sentence doesn't look complete to me.

Quoted 6 lines

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)

Quoted 6 lines

Work around this by preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.
Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by Arnd Bergmann <[email protected]>

Small style comment below, with that:

Reviewed-by Manivannan Sadhasivam <[email protected]>

Quoted 11 lines

---
v2: rebase on top of dmaengine tree
---
 drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
drivers/dma/dw-edma/dw-edma-v0-debugfs.c +0 -0
index 42380bf64a70..6542060bd01a 100644

drivers/dma/dw-edma/dw-edma-v0-debugfs.c static void dw_edma_debugfs_regs_ch(struct dw_edma *dw, enum dw_edma_dir dir, · line 140

Quoted 6 lines

drivers/dma/dw-edma/dw-edma-v0-debugfs.c +2 -1

@@ -136,7 +136,8 @@ 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)

For consistency, the function arguments could be wrapped:

static noinline_for_stack void dw_edma_debugfs_regs_wr(struct dw_edma *dw,
struct dentry *dent)

I could see that with the addition of "noinline_for_stack", the arguments are shifted towards the end of the line. But this style matches rest of the functions in this file.

Thanks,
Mani

Quoted 16 lines

drivers/dma/dw-edma/dw-edma-v0-debugfs.c +2 -1

 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

@@ -197,7 +198,8 @@ 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_for_stack void
+dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

Signature · 1 line

2.39.0

Signature · 1 line

மணிவண்ணன் சதாசிவம்

Serge Semin

Reviewed-by on v2 1/1

2023-01-31 07:54 UTC #2 lore raw

In reply to Arnd Bergmann

Quoted 9 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>
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)

Quoted 6 lines

Work around this by preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.
Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by Arnd Bergmann <[email protected]>

Great! Thanks for the patch.

Reviewed-by Serge Semin <[email protected]>

-Serge(y)

Quoted 33 lines

---
v2: rebase on top of dmaengine tree

---
 drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

drivers/dma/dw-edma/dw-edma-v0-debugfs.c +4 -2

index 42380bf64a70..6542060bd01a 100644
@@ -136,7 +136,8 @@ 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)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

@@ -197,7 +198,8 @@ 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_for_stack void
+dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

Signature · 1 line

2.39.0

Vinod Koul

maintainer

2023-02-10 08:52 UTC #3 lore raw

In reply to Arnd Bergmann

Quoted 9 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>
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)

Quoted 8 lines

Work around this by preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.
Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by Arnd Bergmann <[email protected]>
---
v2: rebase on top of dmaengine tree

I dont have 5c0373eafd83 in my tree, I guess that went thru PCI tree, so I am going to defer this after merge window

Quoted 30 lines

---
 drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

drivers/dma/dw-edma/dw-edma-v0-debugfs.c +4 -2

index 42380bf64a70..6542060bd01a 100644
@@ -136,7 +136,8 @@ 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)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

@@ -197,7 +198,8 @@ 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_for_stack void
+dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

Signature · 1 line

2.39.0

Signature · 1 line

~Vinod

Serge Semin

2023-02-10 12:35 UTC #4 lore raw

Hello Vinod

Quoted 14 lines · Vinod Koul

Quoted 13 lines · Arnd Bergmann
From: Arnd Bergmann <[email protected]>
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 preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.

Quoted 7 lines

Quoted 4 lines
Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by Arnd Bergmann <[email protected]>
---
v2: rebase on top of dmaengine tree
I dont have 5c0373eafd83 in my tree, I guess that went thru PCI tree, so I am going to defer this after merge window

It's in the @Bjorn tree now
https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?h=pci/ctrl/dwc&id=5c0373eafd8334343da22338d8588ed61e8daba0

If you are ok with the fix then @Bjorn could take the patch in to his repo. Right, @Bjorn?

-Serge(y)

Quoted 34 lines

Quoted 31 lines

---
 drivers/dma/dw-edma/dw-edma-v0-debugfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

drivers/dma/dw-edma/dw-edma-v0-debugfs.c +4 -2

index 42380bf64a70..6542060bd01a 100644
@@ -136,7 +136,8 @@ 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)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

@@ -197,7 +198,8 @@ 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_for_stack void
+dw_edma_debugfs_regs_rd(struct dw_edma *dw, struct dentry *dent)
 {
 	const struct dw_edma_debugfs_entry debugfs_regs[] = {
 		/* eDMA global registers */

Signature · 1 line

2.39.0

Signature · 1 line

~Vinod

Vinod Koul

maintainer Acked-by

2023-02-10 15:25 UTC #5 lore raw

Quoted 22 lines · Serge Semin

Hello Vinod
Quoted 19 lines · Vinod Koul
Quoted 17 lines · Arnd Bergmann
From: Arnd Bergmann <[email protected]>
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 preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.
Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by Arnd Bergmann <[email protected]>
---
v2: rebase on top of dmaengine tree

Quoted 8 lines

Quoted 2 lines
I dont have 5c0373eafd83 in my tree, I guess that went thru PCI tree, so I am going to defer this after merge window
It's in the @Bjorn tree now
https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?h=pci/ctrl/dwc&id=5c0373eafd8334343da22338d8588ed61e8daba0
If you are ok with the fix then @Bjorn could take the patch in to his repo. Right, @Bjorn?

Sure:

Acked-by Vinod Koul <[email protected]>

Signature · 1 line

~Vinod

Bjorn Helgaas

2023-02-10 23:29 UTC #6 lore raw

In reply to Serge Semin

Quoted 20 lines · Serge Semin

Quoted 19 lines · Vinod Koul
Quoted 17 lines · Arnd Bergmann
From: Arnd Bergmann <[email protected]>
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 preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.
Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by Arnd Bergmann <[email protected]>
---
v2: rebase on top of dmaengine tree

Quoted 8 lines

Quoted 2 lines
I dont have 5c0373eafd83 in my tree, I guess that went thru PCI tree, so I am going to defer this after merge window
It's in the @Bjorn tree now
https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?h=pci/ctrl/dwc&id=5c0373eafd8334343da22338d8588ed61e8daba0
If you are ok with the fix then @Bjorn could take the patch in to his repo. Right, @Bjorn?

Yes, I squashed this into the original patch and tweaked the whitespace per Manivannan's comment.

Note that we've moved to a shared PCI git tree, so the helgaas/pci.git tree is obsolete and will bit rot until we remove it completely.

The new one is:

https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/

Bjorn

Serge Semin

2023-02-12 19:23 UTC #7 lore raw

Quoted 27 lines · Bjorn Helgaas

Quoted 26 lines · Serge Semin
Quoted 14 lines · Vinod Koul
Quoted 13 lines · Arnd Bergmann
From: Arnd Bergmann <[email protected]>
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 preventing dw_edma_debugfs_regs_{wr,rd} from both being inlined together, which cuts the stack frame size in half and makes it fit below the warning limit.
Quoted 7 lines
Quoted 4 lines
Fixes 5c0373eafd83 ("dmaengine: dw-edma: Move eDMA data pointer to debugfs node descriptor")
Signed-off-by Arnd Bergmann <[email protected]>
---
v2: rebase on top of dmaengine tree
I dont have 5c0373eafd83 in my tree, I guess that went thru PCI tree, so I am going to defer this after merge window
It's in the @Bjorn tree now
https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?h=pci/ctrl/dwc&id=5c0373eafd8334343da22338d8588ed61e8daba0

Quoted 6 lines

Quoted 2 lines
If you are ok with the fix then @Bjorn could take the patch in to his repo. Right, @Bjorn?
Yes, I squashed this into the original patch and tweaked the whitespace per Manivannan's comment.

Great! Thanks.

Quoted 7 lines

Note that we've moved to a shared PCI git tree, so the helgaas/pci.git tree is obsolete and will bit rot until we remove it completely.
The new one is:
https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/

Good to know. Thanks again.

-Serge(y)

Quoted 2 lines

Bjorn