diff options
author | 2020-05-28 21:31:08 +0200 | |
---|---|---|
committer | 2020-06-02 21:23:47 -0400 | |
commit | 8c4e0f212398cdd1eb4310a5981d06a723cdd24f (patch) | |
tree | 2f2f804cb107ac2216ad0dada551b71756a5f173 /drivers/target | |
parent | scsi: ufs: ti-j721e-ufs: Fix unwinding of pm_runtime changes (diff) | |
download | linux-8c4e0f212398cdd1eb4310a5981d06a723cdd24f.tar.gz linux-8c4e0f212398cdd1eb4310a5981d06a723cdd24f.tar.bz2 linux-8c4e0f212398cdd1eb4310a5981d06a723cdd24f.zip |
scsi: target: tcmu: Fix size in calls to tcmu_flush_dcache_range
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>
Diffstat (limited to 'drivers/target')
-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 0e281d30d81e..09ce2d1a8f33 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -1007,7 +1007,7 @@ 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)); @@ -1072,7 +1072,7 @@ 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)); |