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Subject[PATCH] cxl/core: Remove cxld_const_init in cxl_decoder_alloc()
Date
Commit 48667f676189 ("cxl/core: Split decoder setup into alloc + add")
aimed to fix a large stack frame warning but from v5 to v6, it
introduced a new instance of the warning due to allocating
cxld_const_init on the stack, which was done due to the use of const on
the nr_target member of the cxl_decoder struct. With ARCH=arm
allmodconfig minus CONFIG_KASAN:

GCC 11.2.0:

drivers/cxl/core/bus.c: In function ‘cxl_decoder_alloc’:
drivers/cxl/core/bus.c:523:1: error: the frame size of 1032 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
523 | }
| ^
cc1: all warnings being treated as errors

Clang 12.0.1:

drivers/cxl/core/bus.c:486:21: error: stack frame size of 1056 bytes in function 'cxl_decoder_alloc' [-Werror,-Wframe-larger-than=]
struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets)
^
1 error generated.

Revert that part of the change, which makes the stack frame of
cxl_decoder_alloc() much more reasonable.

Fixes: 48667f676189 ("cxl/core: Split decoder setup into alloc + add")
Link: https://github.com/ClangBuiltLinux/linux/issues/1539
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
drivers/cxl/core/bus.c | 6 ++----
drivers/cxl/cxl.h | 2 +-
2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c
index 17a4fff029f8..3f9b98ecd18b 100644
--- a/drivers/cxl/core/bus.c
+++ b/drivers/cxl/core/bus.c
@@ -485,9 +485,7 @@ static int decoder_populate_targets(struct cxl_decoder *cxld,

struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets)
{
- struct cxl_decoder *cxld, cxld_const_init = {
- .nr_targets = nr_targets,
- };
+ struct cxl_decoder *cxld;
struct device *dev;
int rc = 0;

@@ -497,13 +495,13 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets)
cxld = kzalloc(struct_size(cxld, target, nr_targets), GFP_KERNEL);
if (!cxld)
return ERR_PTR(-ENOMEM);
- memcpy(cxld, &cxld_const_init, sizeof(cxld_const_init));

rc = ida_alloc(&port->decoder_ida, GFP_KERNEL);
if (rc < 0)
goto err;

cxld->id = rc;
+ cxld->nr_targets = nr_targets;
dev = &cxld->dev;
device_initialize(dev);
device_set_pm_not_required(dev);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index ab4596f0b751..a5a0be3f088b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -191,7 +191,7 @@ struct cxl_decoder {
int interleave_granularity;
enum cxl_decoder_type target_type;
unsigned long flags;
- const int nr_targets;
+ int nr_targets;
struct cxl_dport *target[];
};

base-commit: 53989fad1286e652ea3655ae3367ba698da8d2ff
--
2.34.1

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