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authorAlexander Usyskin <alexander.usyskin@intel.com>2017-02-08 00:41:45 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-10 15:20:44 +0100
commitcb97fbbcac15982406e0c74cd5512a8b6fcf10b3 (patch)
tree67b264d59a72d79e94302b760f591348ecfc0d70 /drivers/misc/mei
parentdd37eed7db0f7607fa41887c11c1e428faa15d0c (diff)
mei: remove support for broken parallel read
Parallel reads from multiple threads on a file descriptor are not well defined and racy. It is safer to return to original behavior and simply fail the additional read. The solution is to remove request for next read credit. Cc: <stable@vger.kernel.org> #4.9 Fixes: ff1586a7ea57 ("mei: enqueue consecutive reads") Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc/mei')
-rw-r--r--drivers/misc/mei/main.c48
1 files changed, 26 insertions, 22 deletions
diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index e1bf54481fd6..9d0b7050c79a 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -182,32 +182,36 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
goto out;
}
- if (rets == -EBUSY &&
- !mei_cl_enqueue_ctrl_wr_cb(cl, length, MEI_FOP_READ, file)) {
- rets = -ENOMEM;
- goto out;
- }
- do {
- mutex_unlock(&dev->device_lock);
-
- if (wait_event_interruptible(cl->rx_wait,
- (!list_empty(&cl->rd_completed)) ||
- (!mei_cl_is_connected(cl)))) {
+again:
+ mutex_unlock(&dev->device_lock);
+ if (wait_event_interruptible(cl->rx_wait,
+ !list_empty(&cl->rd_completed) ||
+ !mei_cl_is_connected(cl))) {
+ if (signal_pending(current))
+ return -EINTR;
+ return -ERESTARTSYS;
+ }
+ mutex_lock(&dev->device_lock);
- if (signal_pending(current))
- return -EINTR;
- return -ERESTARTSYS;
- }
+ if (!mei_cl_is_connected(cl)) {
+ rets = -ENODEV;
+ goto out;
+ }
- mutex_lock(&dev->device_lock);
- if (!mei_cl_is_connected(cl)) {
- rets = -ENODEV;
- goto out;
- }
+ cb = mei_cl_read_cb(cl, file);
+ if (!cb) {
+ /*
+ * For amthif all the waiters are woken up,
+ * but only fp with matching cb->fp get the cb,
+ * the others have to return to wait on read.
+ */
+ if (cl == &dev->iamthif_cl)
+ goto again;
- cb = mei_cl_read_cb(cl, file);
- } while (!cb);
+ rets = 0;
+ goto out;
+ }
copy_buffer:
/* now copy the data to user space */