On (22/12/11 09:24), Bruce Ashfield wrote:
> On 11-12-21 10:07 PM, Zumeng Chen wrote:
> >There are two problems as follows shown:
> >1 ) for TMPFS, nothing need to be done in sys_msync,
> > sys_msync just return 0 for all arches.
> >
> >2 ) But for MIPS CPUs with cache alias(dmesg|grep alias),
> > it maybe has the issue, which reported by msync test
> > suites in ltp-full, when the memory of memset used by
> > msycn01 has cache alias.
> > So, in this situation, we have to flush the related
> > vma to make sure correct read.
>
> Looks good. I'll queue this for the next kernel update.
>
has this been proposed to lkml ?
> Cheers,
>
> Bruce
>
> >
> >Signed-off-by: Zumeng Chen<zumeng.c...@windriver.com>
> >---
> > include/linux/shmem_fs.h | 10 ++++++++++
> > mm/msync.c | 22 +++++++++++++++++++++-
> > mm/shmem.c | 5 +++++
> > 3 files changed, 36 insertions(+), 1 deletions(-)
> >
> >diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> >index aa08fa8..62a2d57 100644
> >--- a/include/linux/shmem_fs.h
> >+++ b/include/linux/shmem_fs.h
> >@@ -12,6 +12,15 @@
> >
> > #define SHMEM_SYMLINK_INLINE_LEN (SHMEM_NR_DIRECT * sizeof(swp_entry_t))
> >
> >+/*
> >+
> >+*/
> >+#ifndef cpu_has_dc_aliases
> >+#define CPU_HAS_CACHE_ALIAS 0
> >+#else
> >+#define CPU_HAS_CACHE_ALIAS cpu_has_dc_aliases
> >+#endif
> >+
> > struct shmem_inode_info {
> > spinlock_t lock;
> > unsigned long flags;
> >@@ -49,6 +58,7 @@ static inline struct shmem_inode_info *SHMEM_I(struct
> >inode *inode)
> > /*
> > * Functions in mm/shmem.c called directly from elsewhere:
> > */
> >+extern int is_shmem_file(struct file *file);
> > extern int init_tmpfs(void);
> > extern int shmem_fill_super(struct super_block *sb, void *data, int
> > silent);
> > extern struct file *shmem_file_setup(const char *name,
> >diff --git a/mm/msync.c b/mm/msync.c
> >index 632df45..84cb068 100644
> >--- a/mm/msync.c
> >+++ b/mm/msync.c
> >@@ -13,6 +13,8 @@
> > #include<linux/file.h>
> > #include<linux/syscalls.h>
> > #include<linux/sched.h>
> >+#include<linux/shmem_fs.h>
> >+#include<asm/cacheflush.h>
> >
> > /*
> > * MS_SYNC syncs the entire file - including mappings.
> >@@ -33,6 +35,7 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len,
> >int, flags)
> > unsigned long end;
> > struct mm_struct *mm = current->mm;
> > struct vm_area_struct *vma;
> >+ struct file *file;
> > int unmapped_error = 0;
> > int error = -EINVAL;
> >
> >@@ -56,8 +59,25 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len,
> >int, flags)
> > */
> > down_read(&mm->mmap_sem);
> > vma = find_vma(mm, start);
> >+
> >+#ifdef CONFIG_TMPFS
> >+ /*
> >+ * For tmpfs, no matter which flag(ASYNC or SYNC) gets from msync,
> >+ * there is not so much thing to do for CPUs without cache alias,
> >+ * But for some CPUs with cache alias, msync has to flush cache
> >+ * explicitly, which makes sure the data coherency between memory
> >+ * file and cache.
> >+ */
> >+ file = vma->vm_file;
> >+ if (is_shmem_file(file)) {
> >+ if(CPU_HAS_CACHE_ALIAS)
> >+ flush_cache_range(vma, start, start+len);
> >+ error = 0;
> >+ goto out_unlock;
> >+ }
> >+#endif
> >+
> > for (;;) {
> >- struct file *file;
> >
> > /* Still start< end. */
> > error = -ENOMEM;
> >diff --git a/mm/shmem.c b/mm/shmem.c
> >index 92e5c15..4fabfac 100644
> >--- a/mm/shmem.c
> >+++ b/mm/shmem.c
> >@@ -2793,6 +2793,11 @@ static struct file_system_type tmpfs_fs_type = {
> > .kill_sb = kill_litter_super,
> > };
> >
> >+int is_shmem_file(struct file *file)
> >+{
> >+ return (file->f_op ==&shmem_file_operations)? 1 : 0;
> >+}
> >+
> > int __init init_tmpfs(void)
> > {
> > int error;
>
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--
-Khem
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