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author | Bodo Stroesser <bstroesser@ts.fujitsu.com> | 2020-05-28 22:31:08 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-09-09 20:04:22 +0300 |
commit | 04414e46923f83b1c870d126eca18c000ff04ba7 (patch) | |
tree | 19e51f512209d3a4bbc0e74c3787c5f06e9d3a7e | |
parent | 92d0750a38b09b5aa65c8b240aaa08f6935b19e9 (diff) | |
download | linux-04414e46923f83b1c870d126eca18c000ff04ba7.tar.xz |
scsi: target: tcmu: Fix size in calls to tcmu_flush_dcache_range
commit 8c4e0f212398cdd1eb4310a5981d06a723cdd24f upstream.
1) If remaining ring space before the end of the ring is smaller then the
next cmd to write, tcmu writes a padding entry which fills the remaining
space at the end of the ring.
Then tcmu calls tcmu_flush_dcache_range() with the size of struct
tcmu_cmd_entry as data length to flush. If the space filled by the
padding was smaller then tcmu_cmd_entry, tcmu_flush_dcache_range() is
called for an address range reaching behind the end of the vmalloc'ed
ring.
tcmu_flush_dcache_range() in a loop calls
flush_dcache_page(virt_to_page(start)); for every page being part of the
range. On x86 the line is optimized out by the compiler, as
flush_dcache_page() is empty on x86.
But I assume the above can cause trouble on other architectures that
really have a flush_dcache_page(). For paddings only the header part of
an entry is relevant due to alignment rules the header always fits in
the remaining space, if padding is needed. So tcmu_flush_dcache_range()
can safely be called with sizeof(entry->hdr) as the length here.
2) After it has written a command to cmd ring, tcmu calls
tcmu_flush_dcache_range() using the size of a struct tcmu_cmd_entry as
data length to flush. But if a command needs many iovecs, the real size
of the command may be bigger then tcmu_cmd_entry, so a part of the
written command is not flushed then.
Link: https://lore.kernel.org/r/20200528193108.9085-1-bstroesser@ts.fujitsu.com
Acked-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/target/target_core_user.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c index 91dbac7446a4..719520fe2d91 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -1018,7 +1018,7 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err) entry->hdr.cmd_id = 0; /* not used for PAD */ entry->hdr.kflags = 0; entry->hdr.uflags = 0; - tcmu_flush_dcache_range(entry, sizeof(*entry)); + tcmu_flush_dcache_range(entry, sizeof(entry->hdr)); UPDATE_HEAD(mb->cmd_head, pad_size, udev->cmdr_size); tcmu_flush_dcache_range(mb, sizeof(*mb)); @@ -1083,7 +1083,7 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err) cdb_off = CMDR_OFF + cmd_head + base_command_size; memcpy((void *) mb + cdb_off, se_cmd->t_task_cdb, scsi_command_size(se_cmd->t_task_cdb)); entry->req.cdb_off = cdb_off; - tcmu_flush_dcache_range(entry, sizeof(*entry)); + tcmu_flush_dcache_range(entry, command_size); UPDATE_HEAD(mb->cmd_head, command_size, udev->cmdr_size); tcmu_flush_dcache_range(mb, sizeof(*mb)); |