| Message ID | 20250214045414.56291-1-kuniyu@amazon.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2,net-next] checkpatch: Discourage a new use of rtnl_lock() variants. | expand |
On 2/14/2025 5:54 AM, Kuniyuki Iwashima wrote: > rtnl_lock() is a "Big Kernel Lock" in the networking slow path > and still serialises most of RTM_(NEW|DEL|SET)* rtnetlink requests. > > Commit 76aed95319da ("rtnetlink: Add per-netns RTNL.") started a > very large, in-progress, effort to make the RTNL lock scope per > network namespace. > > However, there are still some patches that newly use rtnl_lock(), > which is now discouraged, and we need to revisit it later. > > Let's warn about the case by checkpatch. > > The target functions are as follows: > > * rtnl_lock() > * rtnl_trylock() > * rtnl_lock_interruptible() > * rtnl_lock_killable() > > and the warning will be like: > > WARNING: A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants > #18: FILE: net/core/rtnetlink.c:79: > + rtnl_lock(); > > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> > Reviewed-by: Simon Horman <horms@kernel.org> > --- > v2: > * Remove unnecessary "^\+.*" > * Match "rtnl_lock ()" > > v1: https://lore.kernel.org/netdev/20250211070447.25001-1-kuniyu@amazon.com/ > --- > scripts/checkpatch.pl | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl > index 7b28ad331742..eca4f082ac3f 100755 > --- a/scripts/checkpatch.pl > +++ b/scripts/checkpatch.pl > @@ -6995,6 +6995,12 @@ sub process { > # } > # } > > +# A new use of rtnl_lock() is discouraged as it's being converted to rtnl_net_lock(net). > + if ($line =~ /\brtnl_(try)?lock(_interruptible|_killable)?\s*\(\)/) { > + WARN("rtnl_lock()", > + "A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants\n" . $herecurr); > + } > + > # strcpy uses that should likely be strscpy > if ($line =~ /\bstrcpy\s*\(/) { > WARN("STRCPY", Reviewed-by: Mateusz Polchlopek <mateusz.polchlopek@intel.com>
On Fri, 2025-02-14 at 10:24 +0100, Mateusz Polchlopek wrote: > > On 2/14/2025 5:54 AM, Kuniyuki Iwashima wrote: > > rtnl_lock() is a "Big Kernel Lock" in the networking slow path > > and still serialises most of RTM_(NEW|DEL|SET)* rtnetlink requests. > > > > Commit 76aed95319da ("rtnetlink: Add per-netns RTNL.") started a > > very large, in-progress, effort to make the RTNL lock scope per > > network namespace. > > > > However, there are still some patches that newly use rtnl_lock(), > > which is now discouraged, and we need to revisit it later. > > > > Let's warn about the case by checkpatch. > > > > The target functions are as follows: > > > > * rtnl_lock() > > * rtnl_trylock() > > * rtnl_lock_interruptible() > > * rtnl_lock_killable() > > > > and the warning will be like: > > > > WARNING: A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants > > #18: FILE: net/core/rtnetlink.c:79: > > + rtnl_lock(); > > > > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> > > Reviewed-by: Simon Horman <horms@kernel.org> > > --- > > v2: > > * Remove unnecessary "^\+.*" > > * Match "rtnl_lock ()" > > > > v1: https://lore.kernel.org/netdev/20250211070447.25001-1-kuniyu@amazon.com/ > > --- > > scripts/checkpatch.pl | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl [] > > @@ -6995,6 +6995,12 @@ sub process { > > # } > > # } > > > > +# A new use of rtnl_lock() is discouraged as it's being converted to rtnl_net_lock(net). > > + if ($line =~ /\brtnl_(try)?lock(_interruptible|_killable)?\s*\(\)/) { > > + WARN("rtnl_lock()", > > + "A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants\n" . $herecurr); UPPER_CASE ALPHANUMERIC only for the key value please and there could be whitespace between the parentheses Perhaps: if ($line =~ /\brtnl_((?:try)?lock(?:_interruptible|_killable)?)\s*\(\s*\)/) { WARN("RTNL_LOCK", "New use of rtnl_$1, prefer rtnl_net_$1(net)\n" . $herecurr); } though there doesn't seem to be any uses of interruptible variants in the tree I looked at.
On Fri, Feb 14, 2025 at 5:54 AM Kuniyuki Iwashima <kuniyu@amazon.com> wrote: > > rtnl_lock() is a "Big Kernel Lock" in the networking slow path > and still serialises most of RTM_(NEW|DEL|SET)* rtnetlink requests. > > Commit 76aed95319da ("rtnetlink: Add per-netns RTNL.") started a > very large, in-progress, effort to make the RTNL lock scope per > network namespace. > > However, there are still some patches that newly use rtnl_lock(), > which is now discouraged, and we need to revisit it later. > > Let's warn about the case by checkpatch. > > The target functions are as follows: > > * rtnl_lock() > * rtnl_trylock() > * rtnl_lock_interruptible() > * rtnl_lock_killable() > > and the warning will be like: > > WARNING: A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants > #18: FILE: net/core/rtnetlink.c:79: > + rtnl_lock(); I do wonder if this is not premature. After all, we have nothing in Documentation/ yet about this.
From: Eric Dumazet <edumazet@google.com> Date: Fri, 14 Feb 2025 15:15:48 +0100 > On Fri, Feb 14, 2025 at 5:54 AM Kuniyuki Iwashima <kuniyu@amazon.com> wrote: > > > > rtnl_lock() is a "Big Kernel Lock" in the networking slow path > > and still serialises most of RTM_(NEW|DEL|SET)* rtnetlink requests. > > > > Commit 76aed95319da ("rtnetlink: Add per-netns RTNL.") started a > > very large, in-progress, effort to make the RTNL lock scope per > > network namespace. > > > > However, there are still some patches that newly use rtnl_lock(), > > which is now discouraged, and we need to revisit it later. > > > > Let's warn about the case by checkpatch. > > > > The target functions are as follows: > > > > * rtnl_lock() > > * rtnl_trylock() > > * rtnl_lock_interruptible() > > * rtnl_lock_killable() > > > > and the warning will be like: > > > > WARNING: A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants > > #18: FILE: net/core/rtnetlink.c:79: > > + rtnl_lock(); > > I do wonder if this is not premature. > > After all, we have nothing in Documentation/ yet about this. Fair point. I'll defer this patch at least until rtnetlink handlers are fully converted and the left thing to do is almost replacing existing RTNL, then I'll repost with a small doc.
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 7b28ad331742..eca4f082ac3f 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6995,6 +6995,12 @@ sub process { # } # } +# A new use of rtnl_lock() is discouraged as it's being converted to rtnl_net_lock(net). + if ($line =~ /\brtnl_(try)?lock(_interruptible|_killable)?\s*\(\)/) { + WARN("rtnl_lock()", + "A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants\n" . $herecurr); + } + # strcpy uses that should likely be strscpy if ($line =~ /\bstrcpy\s*\(/) { WARN("STRCPY",
rtnl_lock() is a "Big Kernel Lock" in the networking slow path and still serialises most of RTM_(NEW|DEL|SET)* rtnetlink requests. Commit 76aed95319da ("rtnetlink: Add per-netns RTNL.") started a very large, in-progress, effort to make the RTNL lock scope per network namespace. However, there are still some patches that newly use rtnl_lock(), which is now discouraged, and we need to revisit it later. Let's warn about the case by checkpatch. The target functions are as follows: * rtnl_lock() * rtnl_trylock() * rtnl_lock_interruptible() * rtnl_lock_killable() and the warning will be like: WARNING: A new use of rtnl_lock() variants is discouraged, try to use rtnl_net_lock(net) variants #18: FILE: net/core/rtnetlink.c:79: + rtnl_lock(); Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Simon Horman <horms@kernel.org> --- v2: * Remove unnecessary "^\+.*" * Match "rtnl_lock ()" v1: https://lore.kernel.org/netdev/20250211070447.25001-1-kuniyu@amazon.com/ --- scripts/checkpatch.pl | 6 ++++++ 1 file changed, 6 insertions(+)