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  1. 08 Apr, 2014 6 commits
    • Russ Cox's avatar
      reflect, runtime: fix crash in GC due to reflect.call + precise GC · 72c5d5e7
      Russ Cox authored 
      Given
        type Outer struct {
                *Inner
                ...
        }
the compiler generates the implementation of (*Outer).M dispatching to
the embedded Inner. The implementation is logically:
        func (p *Outer) M() {
                (p.Inner).M()
        }
but since the only change here is the replacement of one pointer
receiver with another, the actual generated code overwrites the
original receiver with the p.Inner pointer and then jumps to the M
method expecting the *Inner receiver.

During reflect.Value.Call, we create an argument frame and the
associated data structures to describe it to the garbage collector,
populate the frame, call reflect.call to run a function call using
that frame, and then copy the results back out of the frame. The
reflect.call function does a memmove of the frame structure onto the
stack (to set up the inputs), runs the call, and the memmoves the
stack back to the frame structure (to preserve the outputs).

Originally reflect.call did not distinguish inputs from outputs: both
memmoves were for the full stack frame. However, in the case where the
called function was one of these wrappers, the rewritten receiver is
almost certainly a different type than the original receiver. This is
not a problem on the stack, where we use the program counter to
determine the type information and understand that during (*Outer).M
the receiver is an *Outer while during (*Inner).M the receiver in the
same memory word is now an *Inner. But in the statically typed
argument frame created by reflect, the receiver is always an *Outer.
Copying the modified receiver pointer off the stack into the frame
will store an *Inner there, and then if a garbage collection happens
to scan that argument frame before it is discarded, it will scan the
*Inner memory as if it were an *Outer. If the two have different
memory layouts, the collection will intepret the memory incorrectly.

Fix by only copying back the results.

Fixes #7725.

LGTM=khr
R=khr
CC=dave, golang-codereviews
https://golang.org/cl/85180043
      72c5d5e7
    • Dmitriy Vyukov's avatar
      runtime/race: more precise handling of channel synchronization · 9e1cadad
      Dmitriy Vyukov authored 
      It turns out there is a relatively common pattern that relies on
inverted channel semaphore:

gate := make(chan bool, N)
for ... {
        // limit concurrency
        gate <- true
        go func() {
                foo(...)
                <-gate
        }()
}
// join all goroutines
for i := 0; i < N; i++ {
        gate <- true
}

So handle synchronization on inverted semaphores with cap>1.
Fixes #7718.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/84880046
      9e1cadad
    • Ian Lance Taylor's avatar
      liblink: remove code that is never executed · f4ecfaa4
      Ian Lance Taylor authored 
      This code tests linkmode == LinkExternal but is only invoked
by the compiler/assembler, not the linker.

Update #7164

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/85080043
      f4ecfaa4
    • Rob Pike's avatar
      doc/go1.3.html: drop support for windows 2000 · 78025fb2
      Rob Pike authored 
      LGTM=bradfitz, alex.brainman
R=golang-codereviews, bradfitz, alex.brainman
CC=golang-codereviews
https://golang.org/cl/85190043
      78025fb2
    • Keith Randall's avatar
      runtime: make sure associated defers are copyable before trying to copy a stack. · fc6753c7
      Keith Randall authored 
      Defers generated from cgo lie to us about their argument layout.
Mark those defers as not copyable.

CL 83820043 contains an additional test for this code and should be
checked in (and enabled) after this change is in.

Fixes bug 7695.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/84740043
      fc6753c7
    • Keith Randall's avatar
      runtime: fix heapdump bugs. · af923df8
      Keith Randall authored 
      Iterate the right number of times in arrays and channels.
Handle channels with zero-sized objects in them.
Output longer type names if we have them.
Compute argument offset correctly.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/82980043
      af923df8
  3. 07 Apr, 2014 8 commits
  5. 06 Apr, 2014 2 commits
  7. 04 Apr, 2014 10 commits
  9. 03 Apr, 2014 14 commits