Summary: ntfa: fix deadlock situation due to saNtfFinalize V2[#1521] Review request for Trac Ticket(s): <<IF ANY LIST THE #>> Peer Reviewer(s): <<LIST THE TECH REVIEWER(S) / MAINTAINER(S) HERE>> Pull request to: <<LIST THE PERSON WITH PUSH ACCESS HERE>> Affected branch(es): <<LIST ALL AFFECTED BRANCH(ES)>> Development branch: <<IF ANY GIVE THE REPO URL>>
-------------------------------- Impacted area Impact y/n -------------------------------- Docs n Build system n RPM/packaging n Configuration files n Startup scripts n SAF services n OpenSAF services n Core libraries n Samples n Tests n Other n Comments (indicate scope for each "y" above): --------------------------------------------- Incorporating some comments given by Lennart. In this version2: -comment is added in function header of saNtfFinalize(). -two test cases is added for saNtfFinalize(). changeset ae56e045cad15d995a4531b120e1564be3142084 Author: [email protected] Date: Wed, 14 Oct 2015 14:48:22 +0530 ntfa: fix deadlock situation due to saNtfFinalize [#1521]. Generally any API called after finalize returns with BAD_HANDLE. But in a multi-threaded application, deadlock situation may arise between saNtfFinalize() with saNtfNotificationUnsubscribe(), or with saNtfStateChangeNotificationAllocate(), or with and saNtfPtrValAllocate(). After getting successful response from the server, saNtfFinalize() takes lock on ntfa_cb.cb_lock and tries to free all the handles and resources. Here it gets block in ntfa_hdl_rec_del() ---->ncshm_destroy_hdl() (actually in in ncshm_destroy_hdl()--->hm_block_me())) as client_handle is in use by other threads and waits for it to get released. At the same time, one of the above three APIS may be waiting for taking the lock on ntfa_cb.cb_lock which is not avialable as it is taken by saNtfFinalize(). From the solution perspective, the LEAP API where santfFinalize() gets blocked wants other threads to complete thier functionality and release the handle. In this situation, new API calls will return with BAD_HANDLE (LEAP functionality take_handle() fails) and existing API calls which has already taken the client_handle will be able to give back client_handle (LEAP functionality give_handle()). So if the lock is removed from Finalize(), other APIS will be able to complete their call and will return handle one by one which eventually will unblock saNtfFinalize(). changeset 292811a7c5b5d4972618aa3dc1a4388fc3b3bd6a Author: [email protected] Date: Wed, 14 Oct 2015 14:48:44 +0530 tests/ntf: add test cases for saNtfFinalize [#1521]. First test (saNtfFinalize_04) will subscribe with NTF after successful initialization. After this it will try to unsubscribe for notification in a separate thread while main thread will try to finalize with NTF. Here saNtfSubacribe() may get successful or return with BAD_HANDLE. Second test (saNtfFinalize_05) will initialize with notification service. After successful initialization, it will try to allocate state change notification in a separate thread while main thread will try to finalize with NTF. Here saNtfStateChangeNotificationAllocate() may get successful or return with BAD_HANDLE In both the test cases saNtfFinalize() will always be sucessful. Complete diffstat: ------------------ osaf/libs/agents/saf/ntfa/ntfa_api.c | 7 +++- tests/ntfsv/tet_saNtfFinalize.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 111 insertions(+), 2 deletions(-) Testing Commands: ----------------- Executed added test cases 2000 times. Testing, Expected Results: -------------------------- Not observing any deadlock. Conditions of Submission: ------------------------- Ack from any reviewer before RC1 of 4.7. Arch Built Started Linux distro ------------------------------------------- mips n n mips64 n n x86 n n x86_64 y y powerpc n n powerpc64 n n Reviewer Checklist: ------------------- [Submitters: make sure that your review doesn't trigger any checkmarks!] Your checkin has not passed review because (see checked entries): ___ Your RR template is generally incomplete; it has too many blank entries that need proper data filled in. ___ You have failed to nominate the proper persons for review and push. ___ Your patches do not have proper short+long header ___ You have grammar/spelling in your header that is unacceptable. ___ You have exceeded a sensible line length in your headers/comments/text. ___ You have failed to put in a proper Trac Ticket # into your commits. ___ You have incorrectly put/left internal data in your comments/files (i.e. internal bug tracking tool IDs, product names etc) ___ You have not given any evidence of testing beyond basic build tests. 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