This is a more concise approach and guarantees there is
no time window where the struct is uninitialized.
Generated using the following semantic patch:
@@
type T;
identifier X;
@@
- T X;
+ T X = { 0 };
... when exists
(
- memset(&X, 0, sizeof(X));
|
- memset(&X, 0, sizeof(T));
)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Claudio Fontana <cfontana@suse.de>
The updateLock is a R/W lock held by anything which needs to read or
modify the rules associated with an NWFilter.
APIs for defining/undefining NW filters rules hold a write lock on
updateLock.
APIs for creating/deleting NW filter bindings hold a read lock on
updateLock, which prevents define/undefine taking place concurrently.
The problems arise when we attempt to creating two NW filter bindings in
parallel.
Thread 1 can acquire the mutex for filter A
Thread 2 can acquire the mutex for filter B
Consider if filters A and B both reference filters C and D, but in
different orders:
Filter A
-> filter C
-> filter D
Filter B
-> filter D
-> filter C
Thread 1 will try to acquire locks in order A, C, D while thread 1 will
try to acquire in order A, D, C. Deadlock can still occur.
Think we can sort the list of filters before acquiring locks on all of
them ? Nope, we allow arbitrary recursion:
Filter A
-> filter C
-> filter E
-> filter F
-> filter H
-> filter K
-> filter D
-> filter G
-> filter I
So we can't tell from looking at 'A' which filters we're going to
need to lock. We can only see the first level of filters references
and we need to lock those before we can see the second level of
filters, etc.
We could probably come up with some cleverness to address this but
it isn't worth the time investment. It is simpler to just keep the
process of creating NW filter bindings totally serialized.
Using two separate locks for this serialization though is pointless.
Every code path which gets a read(updateLock) will go on to hold
updateMutex. It is simpler to just hold write(updateLock) and
get rid of updateMutex. At that point we don't need updateLock
to be a R/W lock, it can be a plain mutex.
Thus this patch gets rid of the current updateLock and updateMutex
and introduces a new top level updateMutex.
This has a secondary benefit of introducing fairness into the
locking. With a POSIX R/W lock, you get writer starvation if
you have lots of readers. IOW, if we call virNWFilterBIndingCreate
and virNWFilterBindingDelete in a tight loop from a couple of
threads, we can prevent virNWFilterDefine from ever acquiring
a write lock.
Getting rid of the R/W lock gives us FIFO lock acquisition
preventing starvation of any API call servicing.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The current use of an array for nwfilter objects requires
the caller to iterate over all elements to find a filter,
and also requires locking each filter.
Switching to a pair of hash tables enables O(1) lookups
both by name and uuid, with no locking required.
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The comment against the 'updateMutex' refers to a problem with
lock ordering when looking up filters in the virNWFilterObjList
which uses an array. That problem does indeed exist.
Unfortunately it claims that switching to a hash table would
solve the lock ordering problems during instantiation. That
is not correct because there is a second lock ordering
problem related to how we traverse related filters when
instantiating filters. Consider a set of filters:
Filter A:
Reference Filter C
Reference Filter D
Filter B:
Reference Filter D
Reference Filter C
In one example, we lock A, C, D, in the other example
we lock A, D, C.
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The virNWFilterTechDriverForName & virNWFilterUpdateInstantiateFilter
methods are only used within the same source file, so don't need to
be exported.
Reviewed-by: Laine Stump <laine@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Use 'g_clear_pointer(&ptr, g_hash_table_unref)' instead.
In few instances it allows us to also remove explicit clearing of
pointers.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
Use automatic memory freeing for 'tmpvars' and move the allocation of
tmpvars earlier so that we are guaranteed that 'obj' will always be
appended to 'inst->filters' and thus don't need cleanup for it.
By moving the reset of 'inst' to the block when virNWFilterDefToInst
fails we can get rid of the rest of the cleanup section and remove the
'ret' variable.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Construct the 'ruleinst->vars' hash table separately in a temporary
variable so that 'ruleinst' can be allocated on success. This allows us
to get rid of the cleanup section.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Use virAppendElement instead of virInsertElementsN to implement
VIR_APPEND_ELEMENT which allows us to remove error handling as the
only relevant errors were removed when switching to aborting memory
allocation functions.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Historically, we declared pointer type to our types:
typedef struct _virXXX virXXX;
typedef virXXX *virXXXPtr;
But usefulness of such declaration is questionable, at best.
Unfortunately, we can't drop every such declaration - we have to
carry some over, because they are part of public API (e.g.
virDomainPtr). But for internal types - we can do drop them and
use what every other C project uses 'virXXX *'.
This change was generated by a very ugly shell script that
generated sed script which was then called over each file in the
repository. For the shell script refer to the cover letter:
https://listman.redhat.com/archives/libvir-list/2021-March/msg00537.html
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Don't hide our use of GHashTable behind our typedef. This will also
promote the use of glibs hash function directly.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Matt Coleman <matt@datto.com>
All users of virHashTable pass strings as the name/key of the entry.
Make this an official requirement by turning the variables to 'const
char *'.
For any other case it's better to use glib's GHashTable.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
It doesn't make much sense to configure the bucket count in the hash
table for each case specifically. Replace all calls of virHashCreate
with virHashNew which has a pre-set size and remove virHashCreate
completely.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Export the freeing function rather than having a wrapper for the hash
creation function.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Rather than having labels named exit, done, exit_snooprequnlock,
skip_rename, etc, use the standard "cleanup" label. And instead of
err_exit, malformed, tear_down_tmpebchains, use "error".
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
It's possible/probable the callers to virNWFilterInstReset() make it
unnecessary to set the object's nrules to 0 after freeing all its
rules, but that same function is setting nfilters to 0, so let's do
the same for the sake of consistency.
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
The function now does not return an error so we can drop it fully.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
The function now does not return an error so we can drop it fully.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Use G_GNUC_UNUSED from GLib instead of ATTRIBUTE_UNUSED.
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Commit d1a7c08eb changed filter instantiation code to ignore MAC and IP
variables explicitly specified for filter binding. It just replaces
explicit values with values associated with the binding. Before the
commit virNWFilterCreateVarsFrom was used so that explicit value
take precedence. Let's bring old behavior back.
This is useful. For example if domain has two interfaces it makes
sense to list both mac adresses in MAC var of every interface
filterref. So that if guest make a bond of these interfaces
and start sending frames with one of the mac adresses from
both interfaces we can pass outgress traffic from both
interfaces too.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
In many files there are header comments that contain an Author:
statement, supposedly reflecting who originally wrote the code.
In a large collaborative project like libvirt, any non-trivial
file will have been modified by a large number of different
contributors. IOW, the Author: comments are quickly out of date,
omitting people who have made significant contribitions.
In some places Author: lines have been added despite the person
merely being responsible for creating the file by moving existing
code out of another file. IOW, the Author: lines give an incorrect
record of authorship.
With this all in mind, the comments are useless as a means to identify
who to talk to about code in a particular file. Contributors will always
be better off using 'git log' and 'git blame' if they need to find the
author of a particular bit of code.
This commit thus deletes all Author: comments from the source and adds
a rule to prevent them reappearing.
The Copyright headers are similarly misleading and inaccurate, however,
we cannot delete these as they have legal meaning, despite being largely
inaccurate. In addition only the copyright holder is permitted to change
their respective copyright statement.
Reviewed-by: Erik Skultety <eskultet@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Remove the callbacks that the nwfilter driver registers with the domain
object config layer. Instead make the current helper methods call into
the public API for creating/deleting nwfilter bindings.
Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Now that the nwfilter driver keeps a list of bindings that it has
created, there is no need for the complex virt driver callbacks. It is
possible to simply iterate of the list of recorded filter bindings.
This means that rebuilding filters no longer has to acquire any locks on
the virDomainObj objects, as they're never touched.
Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Use the virNWFilterBindingDefPtr struct in the DHCP address snooping code
directly.
Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Use the virNWFilterBindingDefPTr struct in the IP address learning code
directly.
Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Use the virNWFilterBindingDefPtr struct in the gentech driver code
directly.
Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The filter parameters were not correctly free'd when an error hits while
adding to the hash table.
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Various methods return a virNWFilterIPAddrLearnReq struct, but the
callers are only interested in whether the return value is non-NULL.
It is thus preferrable to just return a bool.
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
All the code now just uses the virHashTablePtr type directly.
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This removes the virNWFilterHashTableFree, virNWFilterHashTablePut
and virNWFilterHashTableRemove methods, in favour of just calling
the virHash APIs directly.
The virNWFilterHashTablePut method was unreasonably complex because
the virHashUpdateEntry already knows how to create the entry if it
does not currently exist.
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
The virNWFilterHashTable struct only contains a single virHashTable
member since
commit 293d4fe2f1
Author: Daniel P. Berrange <berrange@redhat.com>
Date: Mon Mar 24 16:35:23 2014 +0000
Remove pointless storage of var names in virNWFilterHashTable
Thus, this struct wrapper adds no real value over just using the
virHashTable directly, but brings the complexity of needing to derefence
the hashtable to call virHash* APIs, and adds extra memory allocation
step.
To minimize code churn this just turns virNWFilterHashTable into a
typedef aliases virHashTable.
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Found by Coverity. If virNWFilterHashTablePut, then the 3rd arg @val
must be free'd since it would be leaked.
This also fixes potential problem on the error path where the caller
could assume the virNWFilterHashTablePut was successful when in fact
it failed leading to other issues.
Rather than using loop break;'s in order to force a return
of rc = -1, let's just return -1 immediately on the various
error paths and then return 0 on the success path.
