From patchwork Thu Jun 5 21:44:49 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Don Breazeal X-Patchwork-Id: 1342 Received: (qmail 14152 invoked by alias); 5 Jun 2014 21:45:16 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 14139 invoked by uid 89); 5 Jun 2014 21:45:16 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL, BAYES_00 autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 05 Jun 2014 21:44:52 +0000 Received: from svr-orw-exc-10.mgc.mentorg.com ([147.34.98.58]) by relay1.mentorg.com with esmtp id 1WsfSr-0000zu-Cr from donb@codesourcery.com for gdb-patches@sourceware.org; Thu, 05 Jun 2014 14:44:49 -0700 Received: from [127.0.0.1] ([172.30.4.134]) by SVR-ORW-EXC-10.mgc.mentorg.com with Microsoft SMTPSVC(6.0.3790.4675); Thu, 5 Jun 2014 14:44:48 -0700 Message-ID: <5390E4D1.2050108@codesourcery.com> Date: Thu, 05 Jun 2014 14:44:49 -0700 From: "Breazeal, Don" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: lgustavo@codesourcery.com, gdb-patches@sourceware.org Subject: Re: [PATCH] Fix for follow-fork: followed child doesn't stop References: <1401920383-10219-1-git-send-email-donb@codesourcery.com> <53906D28.5000404@codesourcery.com> In-Reply-To: <53906D28.5000404@codesourcery.com> X-IsSubscribed: yes Hi Luis, Thanks for the review. >> + if (tp->control.step_resume_breakpoint != NULL) >> + tp->control.step_resume_breakpoint->loc->inserted = 0; > > Maybe add a little more context as to why this conditional is doing what > it is doing? I imagine someone scratching their head to figure this out. > Your description above makes good sense. I added a comment above the conditional. Let me know if it isn't what you had in mind. --snip-- >> + test_follow_fork "parent" "on" "next 2" >> + test_follow_fork "parent" "on" "continue" >> + test_follow_fork "child" "on" "next 2" >> + test_follow_fork "child" "on" "continue" >> + test_follow_fork "parent" "off" "next 2" >> + test_follow_fork "parent" "off" "continue" >> + test_follow_fork "child" "off" "next 2" >> + test_follow_fork "child" "off" "continue" > > Instead of hardcoding calls to tests, what about creating a list of > permutations (follow mode, detach on fork, execution command) and using > them inside a for loop? > > That may be a bit cleaner, but i'm not totally against these calls. > I made the change as you suggested, and also added more comments. --snip-- > > The rest of the test looks good to me. > > Luis > Thanks, the updated patch follows. --Don gdb/ 2014-06-05 Don Breazeal * infrun.c (follow_fork): clear 'inserted' flag in single- step breakpoint. gdb/testsuite/ 2014-06-05 Don Breazeal * gdb.base/foll-fork.exp (default_fork_parent_follow): Deleted procedure. (explicit_fork_parent_follow): Deleted procedure. (explicit_fork_child_follow): Deleted procedure. (test_follow_fork): New procedure. (do_fork_tests): Replace calls to deleted procedures with calls to test_follow_fork and reset GDB for subsequent procedure calls. Using the test program gdb.base/foll-fork.c, with follow-fork-mode set to "child" and detach-on-fork set to "on", stepping or running past the fork call results in the child process running to completion, when it should just finish the single step. This was the result of how the single-step state was transferred from the parent to the child in infrun.c:follow_fork. For the parent, the single-step breakpoint was marked as "inserted" (bp->loc->inserted). The breakpoint is transferred to the child, where it clearly has not been inserted. So when the child process is resumed, GDB doesn't insert the breakpoint and the process runs to completion. The solution was to clear the "inserted" flag when the single-step breakpoint is associated with the child process. Along with the fix above, the coverage of the follow-fork test gdb.base/foll-fork.exp was expanded to 1) cover all the combinations of values for follow-fork-mode and detach-on-fork 2) make sure that both user breakpoints and single-step breakpoints are propagated correctly to the child 3) check that the inferior list has the expected contents after following the fork. This was tested by running the testsuite on a Linux x64 system. --- gdb/infrun.c | 10 ++ gdb/testsuite/gdb.base/foll-fork.exp | 173 ++++++++++++++++++++++------------ 2 files changed, 122 insertions(+), 61 deletions(-) # followed, and continue. Make the catchpoint permanent. diff --git a/gdb/infrun.c b/gdb/infrun.c index 47604c7..689f0cb 100644 --- a/gdb/infrun.c +++ b/gdb/infrun.c @@ -522,6 +522,16 @@ follow_fork (void) tp = inferior_thread (); tp->control.step_resume_breakpoint = step_resume_breakpoint; + + /* We clear the INSERTED flag since the step-resume + breakpoint has not been inserted in the new child + process. This doesn't affect the parent process, + since the breakpoint is a clone of the parent's + breakpoint, which was deleted above after it was + cloned. */ + if (tp->control.step_resume_breakpoint != NULL) + tp->control.step_resume_breakpoint->loc->inserted = 0; + tp->control.step_range_start = step_range_start; tp->control.step_range_end = step_range_end; tp->control.step_frame_id = step_frame_id; diff --git a/gdb/testsuite/gdb.base/foll-fork.exp b/gdb/testsuite/gdb.base/foll-fork.exp index e1201d7..c4ef860 100644 --- a/gdb/testsuite/gdb.base/foll-fork.exp +++ b/gdb/testsuite/gdb.base/foll-fork.exp @@ -53,60 +53,109 @@ proc check_fork_catchpoints {} { } } -proc default_fork_parent_follow {} { +# Test follow-fork to ensure that the correct process is followed, that +# the followed process stops where it is expected to stop, that processes +# are detached (or not) as expected, and that the inferior list has the +# expected contents after following the fork. WHO is the argument to +# the 'set follow-fork-mode' command, DETACH is the argument to the +# 'set detach-on-fork' command, and CMD is the GDB command used to +# execute the program past the fork. If the value of WHO or DETACH is +# 'default', the corresponding GDB command is skipped for that test. +# The value of CMD must be either 'next 2' or 'continue'. +proc test_follow_fork { who detach cmd } { global gdb_prompt + global srcfile + global testfile - gdb_test "show follow-fork" \ - "Debugger response to a program call of fork or vfork is \"parent\".*" \ - "default show parent follow, no catchpoints" + set test_name "follow $who, detach $detach, command \"$cmd\"" - gdb_test "next 2" \ - "Detaching after fork from.*" \ - "default parent follow, no catchpoints" + # Start a new debugger session each time so defaults are legitimate. + clean_restart $testfile - # The child has been detached; allow time for any output it might - # generate to arrive, so that output doesn't get confused with - # any expected debugger output from a subsequent testpoint. - # - exec sleep 1 -} + if ![runto_main] { + untested "could not run to main" + return -1 + } -proc explicit_fork_parent_follow {} { - global gdb_prompt + # The "Detaching..." and "Attaching..." messages may be hidden by + # default. + gdb_test_no_output "set verbose" - gdb_test_no_output "set follow-fork parent" + # Set follow-fork-mode if we aren't using the default. + if {$who == "default"} { + set who "parent" + } else { + gdb_test_no_output "set follow-fork $who" + } gdb_test "show follow-fork" \ - "Debugger response to a program call of fork or vfork is \"parent\"." \ - "explicit show parent follow, no catchpoints" + "Debugger response to a program call of fork or vfork is \"$who\"." \ + "$test_name: show follow-fork" + + # Set detach-on-fork mode if we aren't using the default. + if {$detach == "default"} { + set detach "on" + } else { + gdb_test_no_output "set detach-on-fork $detach" + } - gdb_test "next 2" "Detaching after fork from.*" \ - "explicit parent follow, no catchpoints" + gdb_test "show detach-on-fork" \ + "Whether gdb will detach.* fork is $detach." \ + "$test_name: show detach-on-fork" + + # Set the breakpoint after the fork if we aren't single-stepping + # past the fork. + if {$cmd == "continue"} { + set bp_after_fork [gdb_get_line_number "set breakpoint here"] + gdb_test "break ${srcfile}:$bp_after_fork" \ + "Breakpoint.*, line $bp_after_fork.*" \ + "$test_name: set breakpoint after fork" + } - # The child has been detached; allow time for any output it might - # generate to arrive, so that output doesn't get confused with - # any expected debugger output from a subsequent testpoint. - # - exec sleep 1 -} + # Set up the output we expect to see after we run. + set expected_re "" + if {$who == "child"} { + set expected_re "Attaching after.* fork to.*set breakpoint here.*" + } elseif {$who == "parent" && $detach == "on"} { + set expected_re "Detaching after fork from .*set breakpoint here.*" + } else { + set expected_re ".*set breakpoint here.*" + } -proc explicit_fork_child_follow {} { - global gdb_prompt + # Test running past and following the fork, using the parameters + # set above. + gdb_test $cmd $expected_re "$test_name: $cmd past fork" - gdb_test_no_output "set follow-fork child" + # Check that we have the inferiors arranged correctly after + # following the fork. + if {$who == "parent" && $detach == "on"} { - gdb_test "show follow-fork" \ - "Debugger response to a program call of fork or vfork is \"child\"." \ - "explicit show child follow, no catchpoints" + # Follow parent / detach child: the only inferior is the parent. + gdb_test "info inferior" "\\* 1 .* process.*" \ + "$test_name: info inferiors" - gdb_test "next 2" "Attaching after.* fork to.*" \ - "explicit child follow, no catchpoints" + } elseif {$who == "parent" && $detach == "off"} { - # The child has been detached; allow time for any output it might - # generate to arrive, so that output doesn't get confused with - # any gdb_expected debugger output from a subsequent testpoint. - # - exec sleep 1 + # Follow parent / keep child: two inferiors under debug, the + # parent is the current inferior. + gdb_test "info inferior" " 2 .*process.*\\* 1 .*process.*" \ + "$test_name: info inferiors" + + } elseif {$who == "child" && $detach == "on"} { + + # Follow child / detach parent: the child is under debug and is + # the current inferior. The parent is listed but is not under + # debug. + gdb_test "info inferior" "\\* 2 .*process.* 1 .*.*" \ + "$test_name: info inferiors" + + } elseif {$who == "child" && $detach == "off"} { + + # Follow parent / keep child: two inferiors under debug, the + # child is the current inferior. + gdb_test "info inferior" "\\* 2 .*process.* 1 .*process.*" \ + "$test_name: info inferiors" + } } proc catch_fork_child_follow {} { @@ -254,6 +303,7 @@ proc tcatch_fork_parent_follow {} { proc do_fork_tests {} { global gdb_prompt + global testfile # Verify that help is available for "set follow-fork-mode". # @@ -286,31 +336,32 @@ By default, the debugger will follow the parent process..*" \ # fork-following is supported. if [runto_main] then { check_fork_catchpoints } - # Test the default behaviour, which is to follow the parent of a - # fork, and detach from the child. Do this without catchpoints. - # - if [runto_main] then { default_fork_parent_follow } - - # Test the ability to explicitly follow the parent of a fork, and - # detach from the child. Do this without catchpoints. + # Test the basic follow-fork functionality using all combinations of + # values for follow-fork-mode and detach-on-fork, using either a + # breakpoint or single-step to execute past the fork. # - if [runto_main] then { explicit_fork_parent_follow } + # The first two tests should be sufficient to test the defaults. + # There is no need to test using the defaults in other permutations + # (e.g. "default" "on", "parent" "default", etc.). + set cases [list [list "default" "default" "next 2"] \ + [list "default" "default" "continue"] \ + [list "parent" "on" "next 2"] \ + [list "parent" "on" "continue"] \ + [list "child" "on" "next 2"] \ + [list "child" "on" "continue"] \ + [list "parent" "off" "next 2"] \ + [list "parent" "off" "continue"] \ + [list "child" "off" "next 2"] \ + [list "child" "off" "continue"]] + foreach args $cases { + test_follow_fork [lindex $args 0] [lindex $args 1] [lindex $args 2] + } - # Test the ability to follow the child of a fork, and detach from - # the parent. Do this without catchpoints. - # - if [runto_main] then { explicit_fork_child_follow } + # Catchpoint tests. - # Test the ability to follow both child and parent of a fork. Do - # this without catchpoints. - # ??rehrauer: NYI. Will add testpoints here when implemented. - # - - # Test the ability to have the debugger ask the user at fork-time - # whether to follow the parent, child or both. Do this without - # catchpoints. - # ??rehrauer: NYI. Will add testpoints here when implemented. - # + # Restart to eliminate any effects of the follow-fork tests. + clean_restart $testfile + gdb_test_no_output "set verbose" # Test the ability to catch a fork, specify that the child be