diff options
| author | Kameron Carr <kameroncarr@linux.microsoft.com> | 2026-10-19 16:09:47 -0700 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2026-10-21 00:00:29 -0700 |
| commit | 10e2eba7ccb507af62bfff72687c8c559fa4d689 (patch) | |
| tree | 115ff8ac43afbb6e93841f03ac0b2c25106e8a93 /include/linux | |
| parent | 1d287c17cc5bfd6386fe0770999be410b248d021 (diff) | |
Drivers: hv: vmbus: Use *_ONCE() to access shared ring buffer indices
The ring buffer read/write indices live in a page shared with the host,
so the compiler must not split, merge or refetch accesses to them. Add
READ_ONCE()/WRITE_ONCE() in hv_set_next_write_location(),
hv_pkt_iter_close(), hv_get_bytes_to_read() and hv_get_bytes_to_write().
The accesses in hv_ringbuffer_get_debuginfo() are left to the next
patch.
Drop hv_get_ring_bufferindices(). It has one caller and is a one-line
expression on the write index. Inlining it moves the access to the call
site, so hv_ringbuffer_write() can reuse its validated snapshot of that
index, old_write, rather than reading the shared memory a second time.
No functional change intended for a well-behaved host.
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Kameron Carr <kameroncarr@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/hyperv.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index 9e109d91aa14..5c6582085b16 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -214,7 +214,7 @@ static inline u32 hv_get_bytes_to_read(const struct hv_ring_buffer_info *rbi) u32 read_loc, write_loc, dsize, read; dsize = rbi->ring_datasize; - read_loc = rbi->ring_buffer->read_index; + read_loc = READ_ONCE(rbi->ring_buffer->read_index); write_loc = READ_ONCE(rbi->ring_buffer->write_index); read = write_loc >= read_loc ? (write_loc - read_loc) : @@ -229,7 +229,7 @@ static inline u32 hv_get_bytes_to_write(const struct hv_ring_buffer_info *rbi) dsize = rbi->ring_datasize; read_loc = READ_ONCE(rbi->ring_buffer->read_index); - write_loc = rbi->ring_buffer->write_index; + write_loc = READ_ONCE(rbi->ring_buffer->write_index); write = write_loc >= read_loc ? dsize - (write_loc - read_loc) : read_loc - write_loc; |