| commit | 2b283cedef2a62e37b7422ef3badc7b758bd26c8 | [log] [tgz] |
|---|---|---|
| author | Daniel Theophanes <kardianos@gmail.com> | Fri Jan 20 17:12:50 2017 -0800 |
| committer | Brad Fitzpatrick <bradfitz@golang.org> | Thu Jan 26 06:25:37 2017 +0000 |
| tree | cbcc0b61e8b932e8cbf2010c0d1ff1ffa74f619a | |
| parent | 1cf08182f92698aeba8be040dafb5296707cdbf2 [diff] |
database/sql: fix race when canceling queries immediately Previously the following could happen, though in practice it would be rare. Goroutine 1: (*Tx).QueryContext begins a query, passing in userContext Goroutine 2: (*Tx).awaitDone starts to wait on the context derived from the passed in context Goroutine 1: (*Tx).grabConn returns a valid (*driverConn) The (*driverConn) passes to (*DB).queryConn Goroutine 3: userContext is canceled Goroutine 2: (*Tx).awaitDone unblocks and calls (*Tx).rollback (*driverConn).finalClose obtains dc.Mutex (*driverConn).finalClose sets dc.ci = nil Goroutine 1: (*DB).queryConn obtains dc.Mutex in withLock ctxDriverPrepare accepts dc.ci which is now nil ctxCriverPrepare panics on the nil ci The fix for this is to guard the Tx methods with a RWLock holding it exclusivly when closing the Tx and holding a read lock when executing a query. Fixes #18719 Change-Id: I37aa02c37083c9793dabd28f7f934a1c5cbc05ea Reviewed-on: https://go-review.googlesource.com/35550 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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