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authorLinus Torvalds <torvalds@linux-foundation.org>2015-02-15 10:48:44 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-15 10:48:44 -0800
commit4ba63072b998cc31515cc6305c25f3b808b50c01 (patch)
tree779863511765c70bfd232f676b885f940ba88722 /drivers/hv/hv_fcopy.c
parente29876723f7cb7728f0d6a674d23f92673e9f112 (diff)
parent5fb31cd839c21130c0b2524ceb9244e98dfe10e3 (diff)
downloadlinux-4ba63072b998cc31515cc6305c25f3b808b50c01.tar.bz2
Merge tag 'char-misc-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char / misc patches from Greg KH: "Here's the big char/misc driver update for 3.20-rc1. Lots of little things in here, all described in the changelog. Nothing major or unusual, except maybe the binder selinux stuff, which was all acked by the proper selinux people and they thought it best to come through this tree. All of this has been in linux-next with no reported issues for a while" * tag 'char-misc-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (90 commits) coresight: fix function etm_writel_cp14() parameter order coresight-etm: remove check for unknown Kconfig macro coresight: fixing CPU hwid lookup in device tree coresight: remove the unnecessary function coresight_is_bit_set() coresight: fix the debug AMBA bus name coresight: remove the extra spaces coresight: fix the link between orphan connection and newly added device coresight: remove the unnecessary replicator property coresight: fix the replicator subtype value pdfdocs: Fix 'make pdfdocs' failure for 'uio-howto.tmpl' mcb: Fix error path of mcb_pci_probe virtio/console: verify device has config space ti-st: clean up data types (fix harmless memory corruption) mei: me: release hw from reset only during the reset flow mei: mask interrupt set bit on clean reset bit extcon: max77693: Constify struct regmap_config extcon: adc-jack: Release IIO channel on driver remove extcon: Remove duplicated include from extcon-class.c Drivers: hv: vmbus: hv_process_timer_expiration() can be static Drivers: hv: vmbus: serialize Offer and Rescind offer ...
Diffstat (limited to 'drivers/hv/hv_fcopy.c')
-rw-r--r--drivers/hv/hv_fcopy.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index 23b2ce294c4c..cd453e4b2a07 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -86,6 +86,18 @@ static void fcopy_work_func(struct work_struct *dummy)
* process the pending transaction.
*/
fcopy_respond_to_host(HV_E_FAIL);
+
+ /* In the case the user-space daemon crashes, hangs or is killed, we
+ * need to down the semaphore, otherwise, after the daemon starts next
+ * time, the obsolete data in fcopy_transaction.message or
+ * fcopy_transaction.fcopy_msg will be used immediately.
+ *
+ * NOTE: fcopy_read() happens to get the semaphore (very rare)? We're
+ * still OK, because we've reported the failure to the host.
+ */
+ if (down_trylock(&fcopy_transaction.read_sema))
+ ;
+
}
static int fcopy_handle_handshake(u32 version)
@@ -344,6 +356,14 @@ static int fcopy_open(struct inode *inode, struct file *f)
return 0;
}
+/* XXX: there are still some tricky corner cases, e.g.,
+ * 1) In a SMP guest, when fcopy_release() runs between
+ * schedule_delayed_work() and fcopy_send_data(), there is
+ * still a chance an obsolete message will be queued.
+ *
+ * 2) When the fcopy daemon is running, if we unload the driver,
+ * we'll notice a kernel oops when we kill the daemon later.
+ */
static int fcopy_release(struct inode *inode, struct file *f)
{
/*
@@ -351,6 +371,13 @@ static int fcopy_release(struct inode *inode, struct file *f)
*/
in_hand_shake = true;
opened = false;
+
+ if (cancel_delayed_work_sync(&fcopy_work)) {
+ /* We haven't up()-ed the semaphore(very rare)? */
+ if (down_trylock(&fcopy_transaction.read_sema))
+ ;
+ fcopy_respond_to_host(HV_E_FAIL);
+ }
return 0;
}