Date: Tue, 29 Apr 2025 11:41:48 GMT From: "Bjoern A. Zeeb" <bz@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: df71d2753d00 - stable/14 - LinuxKPI: skbuff: rewrite data allocation to use __kmalloc by default Message-ID: <202504291141.53TBfmR6046126@gitrepo.freebsd.org>
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The branch stable/14 has been updated by bz: URL: https://cgit.FreeBSD.org/src/commit/?id=df71d2753d007c51d1722044877e1a4ade867aa4 commit df71d2753d007c51d1722044877e1a4ade867aa4 Author: Bjoern A. Zeeb <bz@FreeBSD.org> AuthorDate: 2025-04-22 20:53:47 +0000 Commit: Bjoern A. Zeeb <bz@FreeBSD.org> CommitDate: 2025-04-29 10:49:30 +0000 LinuxKPI: skbuff: rewrite data allocation to use __kmalloc by default Put tunable/contigmalloc code under SKB_DMA32_MALLOC and remove the __LP64__ checks for simplicity (apart from the 36bit check as that would overflow the variable with the constant value). busdma still has trouble bouncing contiguous memory with nseg=1 if it is multiple pages. Switch the other code to use __kmalloc() which now automatically provides physically contiguous memory and deals with freeing as well. This code should in theroy be enough now. If people use iwlwifi(4) pre-22000 (9xxx 8xxx ...) chipsets on Laptops with more than 64GB of memory they may see bounce errors as well now. Sposnored by: The FreeBSD Foundation (cherry picked from commit e6c91f8e5be66d774bc07f4055aa38fb2e287ff6) (cherry picked from commit cd649cfc7ab23a8a36218977c60ed20afe48aea9) --- sys/compat/linuxkpi/common/src/linux_skbuff.c | 32 +++++++++++++++++---------- 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/sys/compat/linuxkpi/common/src/linux_skbuff.c b/sys/compat/linuxkpi/common/src/linux_skbuff.c index d454e5fc3ab8..abfb642ba708 100644 --- a/sys/compat/linuxkpi/common/src/linux_skbuff.c +++ b/sys/compat/linuxkpi/common/src/linux_skbuff.c @@ -67,22 +67,26 @@ SYSCTL_INT(_compat_linuxkpi_skb, OID_AUTO, debug, CTLFLAG_RWTUN, static uma_zone_t skbzone; -#ifdef __LP64__ +#define SKB_DMA32_MALLOC +#ifdef SKB_DMA32_MALLOC /* * Realtek wireless drivers (e.g., rtw88) require 32bit DMA in a single segment. * busdma(9) has a hard time providing this currently for 3-ish pages at large * quantities (see lkpi_pci_nseg1_fail in linux_pci.c). * Work around this for now by allowing a tunable to enforce physical addresses - * allocation limits on 64bit platforms using "old-school" contigmalloc(9) to - * avoid bouncing. + * allocation limits using "old-school" contigmalloc(9) to avoid bouncing. + * Note: with the malloc/contigmalloc + kmalloc changes also providing physical + * contiguous memory, and the nseg=1 limit for bouncing we should in theory be + * fine now and not need any of this anymore, however busdma still has troubles + * boncing three contiguous pages so for now this stays. */ static int linuxkpi_skb_memlimit; SYSCTL_INT(_compat_linuxkpi_skb, OID_AUTO, mem_limit, CTLFLAG_RDTUN, &linuxkpi_skb_memlimit, 0, "SKB memory limit: 0=no limit, " "1=32bit, 2=36bit, other=undef (currently 32bit)"); -#endif static MALLOC_DEFINE(M_LKPISKB, "lkpiskb", "Linux KPI skbuff compat"); +#endif struct sk_buff * linuxkpi_alloc_skb(size_t size, gfp_t gfp) @@ -103,20 +107,20 @@ linuxkpi_alloc_skb(size_t size, gfp_t gfp) return (skb); len = size; +#ifdef SKB_DMA32_MALLOC /* * Using our own type here not backing my kmalloc. * We assume no one calls kfree directly on the skb. */ -#ifdef __LP64__ - if (__predict_true(linuxkpi_skb_memlimit == 0)) { - p = malloc(len, M_LKPISKB, linux_check_m_flags(gfp) | M_ZERO); - } else { + if (__predict_false(linuxkpi_skb_memlimit != 0)) { vm_paddr_t high; switch (linuxkpi_skb_memlimit) { +#ifdef __LP64__ case 2: high = (0xfffffffff); /* 1<<36 really. */ break; +#endif case 1: default: high = (0xffffffff); /* 1<<32 really. */ @@ -125,10 +129,9 @@ linuxkpi_alloc_skb(size_t size, gfp_t gfp) len = roundup_pow_of_two(len); p = contigmalloc(len, M_LKPISKB, linux_check_m_flags(gfp) | M_ZERO, 0, high, PAGE_SIZE, 0); - } -#else - p = malloc(len, M_LKPISKB, linux_check_m_flags(gfp) | M_ZERO); + } else #endif + p = __kmalloc(len, linux_check_m_flags(gfp) | M_ZERO); if (p == NULL) { uma_zfree(skbzone, skb); return (NULL); @@ -272,7 +275,12 @@ linuxkpi_kfree_skb(struct sk_buff *skb) skb->head = NULL; } - free(skb->head, M_LKPISKB); +#ifdef SKB_DMA32_MALLOC + if (__predict_false(linuxkpi_skb_memlimit != 0)) + free(skb->head, M_LKPISKB); + else +#endif + kfree(skb->head); uma_zfree(skbzone, skb); }
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