Avoid nested min()/max() which results in egregious macro expansion.
This issue was introduced by commit 867046cc7027 ("minmax: relax check to
allow comparison between unsigned arguments and signed constants") [2].
Work has been done to address the issue of egregious min()/max() macro
expansion in commit 22f546873149 ("minmax: improve macro expansion and type
checking") and related, however it appears that some issues remain on more
tightly constrained systems.
Adjust a few known-bad cases of deeply nested macros to avoid doing so to
mitigate this. Porting the patch first proposed in [1] to Linus's tree.
Running an allmodconfig build using the methodology described in [2] we
observe a 35 MiB reduction in generated code.
The difference is much more significant prior to recent minmax fixes which
were not backported. As per [1] prior these the reduction is more like 200
MiB.
This resolves an issue with slackware 15.0 32-bit compilation as reported
by Richard Narron.
Presumably the min/max fixups would be difficult to backport, this patch
should be easier and fix's Richard's problem in 5.15.
[0]:https://lore.kernel.org/all/b97faef60ad24922b530241c5d7c933c@xxxxxxxxxxxxxxxx/
[1]:https://lore.kernel.org/lkml/5882b96e-1287-4390-8174-3316d39038ef@lucifer.local/
[2]:https://lore.kernel.org/linux-mm/36aa2cad-1db1-4abf-8dd2-fb20484aabc3@lucifer.local/
Reported-by: Richard Narron <richard@xxxxxxxxxx>
Closes: https://lore.kernel.org/all/4a5321bd-b1f-1832-f0c-cea8694dc5aa@xxxxxxxxxx/
Fixes: 867046cc7027 ("minmax: relax check to allow comparison between unsigned arguments and signed constants")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
---
drivers/net/ethernet/marvell/mvpp2/mvpp2.h | 2 +-
.../staging/media/atomisp/pci/sh_css_frac.h | 26 ++++++++++++++-----
include/linux/skbuff.h | 6 ++++-
3 files changed, 25 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
index e809f91c08fb..8b431f90efc3 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2.h
@@ -23,7 +23,7 @@
/* The PacketOffset field is measured in units of 32 bytes and is 3 bits wide,
* so the maximum offset is 7 * 32 = 224
*/
-#define MVPP2_SKB_HEADROOM min(max(XDP_PACKET_HEADROOM, NET_SKB_PAD), 224)
+#define MVPP2_SKB_HEADROOM clamp_t(int, XDP_PACKET_HEADROOM, NET_SKB_PAD, 224)
#define MVPP2_XDP_PASS 0
#define MVPP2_XDP_DROPPED BIT(0)
diff --git a/drivers/staging/media/atomisp/pci/sh_css_frac.h b/drivers/staging/media/atomisp/pci/sh_css_frac.h
index b90b5b330dfa..a973394c5bc0 100644
--- a/drivers/staging/media/atomisp/pci/sh_css_frac.h
+++ b/drivers/staging/media/atomisp/pci/sh_css_frac.h
@@ -32,12 +32,24 @@
#define uISP_VAL_MAX ((unsigned int)((1 << uISP_REG_BIT) - 1))
/* a:fraction bits for 16bit precision, b:fraction bits for ISP precision */
-#define sDIGIT_FITTING(v, a, b) \
- min_t(int, max_t(int, (((v) >> sSHIFT) >> max(sFRACTION_BITS_FITTING(a) - (b), 0)), \
- sISP_VAL_MIN), sISP_VAL_MAX)
-#define uDIGIT_FITTING(v, a, b) \
- min((unsigned int)max((unsigned)(((v) >> uSHIFT) \
- >> max((int)(uFRACTION_BITS_FITTING(a) - (b)), 0)), \
- uISP_VAL_MIN), uISP_VAL_MAX)
+static inline int sDIGIT_FITTING(short v, int a, int b)
+{
+ int fit_shift = sFRACTION_BITS_FITTING(a) - b;
+
+ v >>= sSHIFT;
+ v >>= fit_shift > 0 ? fit_shift : 0;
+
+ return clamp_t(int, v, sISP_VAL_MIN, sISP_VAL_MAX);
+}
+
+static inline unsigned int uDIGIT_FITTING(unsigned int v, int a, int b)
+{
+ int fit_shift = uFRACTION_BITS_FITTING(a) - b;
+
+ v >>= uSHIFT;
+ v >>= fit_shift > 0 ? fit_shift : 0;
+
+ return clamp_t(unsigned int, v, uISP_VAL_MIN, uISP_VAL_MAX);
+}
#endif /* __SH_CSS_FRAC_H */
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 29c3ea5b6e93..d53b296df504 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3164,7 +3164,11 @@ static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
* NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
*/
#ifndef NET_SKB_PAD
-#define NET_SKB_PAD max(32, L1_CACHE_BYTES)
+#if L1_CACHE_BYTES < 32
+#define NET_SKB_PAD 32
+#else
+#define NET_SKB_PAD L1_CACHE_BYTES
+#endif
#endif
int ___pskb_trim(struct sk_buff *skb, unsigned int len);
--
2.46.0
