diff mbox series

[v3,06/19,5.15.y] minmax: add a few more MIN_T/MAX_T users

Message ID 20251008152946.29285-7-farbere@amazon.com
State Not Applicable
Headers show
Series Backport minmax.h updates from v6.17-rc7 | expand

Commit Message

Farber, Eliav Oct. 8, 2025, 3:29 p.m. UTC 
From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit 4477b39c32fdc03363affef4b11d48391e6dc9ff ]

Commit 3a7e02c040b1 ("minmax: avoid overly complicated constant
expressions in VM code") added the simpler MIN_T/MAX_T macros in order
to avoid some excessive expansion from the rather complicated regular
min/max macros.

The complexity of those macros stems from two issues:

 (a) trying to use them in situations that require a C constant
     expression (in static initializers and for array sizes)

 (b) the type sanity checking

and MIN_T/MAX_T avoids both of these issues.

Now, in the whole (long) discussion about all this, it was pointed out
that the whole type sanity checking is entirely unnecessary for
min_t/max_t which get a fixed type that the comparison is done in.

But that still leaves min_t/max_t unnecessarily complicated due to
worries about the C constant expression case.

However, it turns out that there really aren't very many cases that use
min_t/max_t for this, and we can just force-convert those.

This does exactly that.

Which in turn will then allow for much simpler implementations of
min_t()/max_t().  All the usual "macros in all upper case will evaluate
the arguments multiple times" rules apply.

We should do all the same things for the regular min/max() vs MIN/MAX()
cases, but that has the added complexity of various drivers defining
their own local versions of MIN/MAX, so that needs another level of
fixes first.

Link: https://lore.kernel.org/all/b47fad1d0cf8449886ad148f8c013dae@AcuMS.aculab.com/
Cc: David Laight <David.Laight@aculab.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Eliav Farber <farbere@amazon.com>
---
V2 -> V3:
Fix fs/erofs/zdata.h to use MIN_T instead of min_t to fix build on the
following patch:
In file included from ./include/linux/kernel.h:16,
                 from ./include/linux/list.h:9,
                 from ./include/linux/wait.h:7,
                 from ./include/linux/wait_bit.h:8,
                 from ./include/linux/fs.h:6,
                 from fs/erofs/internal.h:10,
                 from fs/erofs/zdata.h:9,
                 from fs/erofs/zdata.c:6:
fs/erofs/zdata.c: In function ‘z_erofs_decompress_pcluster’:
fs/erofs/zdata.h:185:61: error: ISO C90 forbids variable length array ‘pages_onstack’ [-Werror=vla]
  185 |         min_t(unsigned int, THREAD_SIZE / 8 / sizeof(struct page *), 96U)
      |                                                             ^~~~
./include/linux/minmax.h:49:23: note: in definition of macro ‘__cmp_once_unique’
   49 |         ({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
      |                       ^
./include/linux/minmax.h:164:27: note: in expansion of macro ‘__cmp_once’
  164 | #define min_t(type, x, y) __cmp_once(min, type, x, y)
      |                           ^~~~~~~~~~
fs/erofs/zdata.h:185:9: note: in expansion of macro ‘min_t’
  185 |         min_t(unsigned int, THREAD_SIZE / 8 / sizeof(struct page *), 96U)
      |         ^~~~~
fs/erofs/zdata.c:847:36: note: in expansion of macro ‘Z_EROFS_VMAP_ONSTACK_PAGES’
  847 |         struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
      |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

V1 -> V2:
Use `[ Upstream commit <HASH> ]` instead of `commit <HASH> upstream.`
like in all other patches.

 arch/x86/mm/pgtable.c                             | 2 +-
 drivers/edac/sb_edac.c                            | 4 ++--
 drivers/gpu/drm/drm_color_mgmt.c                  | 2 +-
 drivers/md/dm-integrity.c                         | 2 +-
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
 fs/erofs/zdata.h                                  | 2 +-
 net/ipv4/proc.c                                   | 2 +-
 net/ipv6/proc.c                                   | 2 +-
 8 files changed, 9 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 3481b35cb4ec..e649161eb6fc 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -107,7 +107,7 @@  static inline void pgd_list_del(pgd_t *pgd)
 #define UNSHARED_PTRS_PER_PGD				\
 	(SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
 #define MAX_UNSHARED_PTRS_PER_PGD			\
-	max_t(size_t, KERNEL_PGD_BOUNDARY, PTRS_PER_PGD)
+	MAX_T(size_t, KERNEL_PGD_BOUNDARY, PTRS_PER_PGD)
 
 
 static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
diff --git a/drivers/edac/sb_edac.c b/drivers/edac/sb_edac.c
index 1522d4aa2ca6..714020e7405a 100644
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -109,8 +109,8 @@  static const u32 knl_interleave_list[] = {
 	0x104, 0x10c, 0x114, 0x11c,   /* 20-23 */
 };
 #define MAX_INTERLEAVE							\
-	(max_t(unsigned int, ARRAY_SIZE(sbridge_interleave_list),	\
-	       max_t(unsigned int, ARRAY_SIZE(ibridge_interleave_list),	\
+	(MAX_T(unsigned int, ARRAY_SIZE(sbridge_interleave_list),	\
+	       MAX_T(unsigned int, ARRAY_SIZE(ibridge_interleave_list),	\
 		     ARRAY_SIZE(knl_interleave_list))))
 
 struct interleave_pkg {
diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index bb14f488c8f6..1ff572d8744e 100644
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -528,7 +528,7 @@  int drm_plane_create_color_properties(struct drm_plane *plane,
 {
 	struct drm_device *dev = plane->dev;
 	struct drm_property *prop;
-	struct drm_prop_enum_list enum_list[max_t(int, DRM_COLOR_ENCODING_MAX,
+	struct drm_prop_enum_list enum_list[MAX_T(int, DRM_COLOR_ENCODING_MAX,
 						       DRM_COLOR_RANGE_MAX)];
 	int i, len;
 
diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index e9d553eea9cd..8e2b00536c3e 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -2536,7 +2536,7 @@  static void do_journal_write(struct dm_integrity_c *ic, unsigned write_start,
 				    unlikely(from_replay) &&
 #endif
 				    ic->internal_hash) {
-					char test_tag[max_t(size_t, HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
+					char test_tag[MAX_T(size_t, HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
 
 					integrity_sector_checksum(ic, sec + ((l - j) << ic->sb->log2_sectors_per_block),
 								  (char *)access_journal_data(ic, i, l), test_tag);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 2478caeec763..21cc8cd9e023 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2805,7 +2805,7 @@  static void stmmac_dma_interrupt(struct stmmac_priv *priv)
 	u32 channels_to_check = tx_channel_count > rx_channel_count ?
 				tx_channel_count : rx_channel_count;
 	u32 chan;
-	int status[max_t(u32, MTL_MAX_TX_QUEUES, MTL_MAX_RX_QUEUES)];
+	int status[MAX_T(u32, MTL_MAX_TX_QUEUES, MTL_MAX_RX_QUEUES)];
 
 	/* Make sure we never check beyond our status buffer. */
 	if (WARN_ON_ONCE(channels_to_check > ARRAY_SIZE(status)))
diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
index 3a008f1b9f78..43876fd8a2cb 100644
--- a/fs/erofs/zdata.h
+++ b/fs/erofs/zdata.h
@@ -182,7 +182,7 @@  static inline void z_erofs_onlinepage_endio(struct page *page)
 }
 
 #define Z_EROFS_VMAP_ONSTACK_PAGES	\
-	min_t(unsigned int, THREAD_SIZE / 8 / sizeof(struct page *), 96U)
+	MIN_T(unsigned int, THREAD_SIZE / 8 / sizeof(struct page *), 96U)
 #define Z_EROFS_VMAP_GLOBAL_PAGES	2048
 
 #endif
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 4b9280a3b673..d849f61b7519 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -43,7 +43,7 @@ 
 #include <net/sock.h>
 #include <net/raw.h>
 
-#define TCPUDP_MIB_MAX max_t(u32, UDP_MIB_MAX, TCP_MIB_MAX)
+#define TCPUDP_MIB_MAX MAX_T(u32, UDP_MIB_MAX, TCP_MIB_MAX)
 
 /*
  *	Report socket allocation statistics [mea@utu.fi]
diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index d6306aa46bb1..e07c43bd5cb0 100644
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -27,7 +27,7 @@ 
 #include <net/ipv6.h>
 
 #define MAX4(a, b, c, d) \
-	max_t(u32, max_t(u32, a, b), max_t(u32, c, d))
+	MAX_T(u32, MAX_T(u32, a, b), MAX_T(u32, c, d))
 #define SNMP_MIB_MAX MAX4(UDP_MIB_MAX, TCP_MIB_MAX, \
 			IPSTATS_MIB_MAX, ICMP_MIB_MAX)