Messages in this thread Patch in this message | | | Subject | Re: False positive for 'Possible unnecessary KERN_ERR' warning in checkpatch | From | Joe Perches <> | Date | Wed, 15 Sep 2021 20:46:22 -0700 |
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On Tue, 2021-09-14 at 18:05 +0200, Niklas Söderlund wrote: > Hi Joe, > > Maybe you are already aware of this, but in case you are not. > > The issue is the checkpatch check for unnecessary KERN_<LEVEL> for log > functions. If a single line contains a statement that match a log > function name from $logFunctions, such as foo_err() and the same line > contains a KERN_<LEVEL> statement the 'WARNING: Possible unnecessary > KERN_ERR' is triggered. This is true even if the KERN_<LEVEL> statement > is not part of the arguments to the foo_err() definition that triggers > the first part of the check. > > This can be demonstrated by, > > ./scripts/checkpatch.pl --mailback --git c821e617896e99b8 > > Where we get (among others) the warning, > > WARNING: Possible unnecessary KERN_ERR > #38: FILE: drivers/net/ethernet/netronome/nfp/nfp_net.h:63: > +#define nn_err(nn, fmt, args...) nn_pr(nn, KERN_ERR, fmt, ## args) > > Looking at the code in checkpatch.pl we have, > > our $logFunctions = qr{(?x: > printk(?:_ratelimited|_once|_deferred_once|_deferred|)| > (?:[a-z0-9]+_){1,2}(?:printk|emerg|alert|crit|err|warning|warn|notice|info|debug|dbg|vdbg|devel|cont|WARN)(?:_ratelimited|_once|)| > TP_printk| > WARN(?:_RATELIMIT|_ONCE|)| > panic| > MODULE_[A-Z_]+| > seq_vprintf|seq_printf|seq_puts > )}; > > ... > > # check for logging functions with KERN_<LEVEL> > if ($line !~ /printk(?:_ratelimited|_once)?\s*\(/ && > $line =~ /\b$logFunctions\s*\(.*\b(KERN_[A-Z]+)\b/) { > my $level = $1; > if (WARN("UNNECESSARY_KERN_LEVEL", > "Possible unnecessary $level\n" . $herecurr) && > $fix) { > $fixed[$fixlinenr] =~ s/\s*$level\s*//; > } > } > > Looking at the line from above that triggers the warning, > > #define nn_err(nn, fmt, args...) nn_pr(nn, KERN_ERR, fmt, ## args) > > We see that the warning is triggers by the regexp but that it matches > the first part on nn_err( and then the second part of on the second > argument to nn_pr, KERN_ERR. I believe this to be a false positive. > > Unfortunately my Perl skills are not good enough to fix the check to only > look for KERN_[A-Z]+ inside the argument list to the log function name > that matches the first part of the regexp. >
I would have avoided it and gotten dynamic debug support at the same time with: --- drivers/net/ethernet/netronome/nfp/nfp_net.h | 48 ++++++++++++++-------------- 1 file changed, 24 insertions(+), 24 deletions(-)
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net.h b/drivers/net/ethernet/netronome/nfp/nfp_net.h index df203738511bf..46178a7244ad8 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net.h +++ b/drivers/net/ethernet/netronome/nfp/nfp_net.h @@ -25,32 +25,32 @@ #include "nfp_net_ctrl.h" -#define nn_pr(nn, lvl, fmt, args...) \ - ({ \ - struct nfp_net *__nn = (nn); \ +#define nn_pr(nn, lvl, fmt, ...) \ +({ \ + struct nfp_net *__nn = (nn); \ \ - if (__nn->dp.netdev) \ - netdev_printk(lvl, __nn->dp.netdev, fmt, ## args); \ - else \ - dev_printk(lvl, __nn->dp.dev, "ctrl: " fmt, ## args); \ - }) - -#define nn_err(nn, fmt, args...) nn_pr(nn, KERN_ERR, fmt, ## args) -#define nn_warn(nn, fmt, args...) nn_pr(nn, KERN_WARNING, fmt, ## args) -#define nn_info(nn, fmt, args...) nn_pr(nn, KERN_INFO, fmt, ## args) -#define nn_dbg(nn, fmt, args...) nn_pr(nn, KERN_DEBUG, fmt, ## args) - -#define nn_dp_warn(dp, fmt, args...) \ - ({ \ - struct nfp_net_dp *__dp = (dp); \ + if (__nn->dp.netdev) \ + netdev_##lvl(__nn->dp.netdev, fmt, ##__VA_ARGS__); \ + else \ + dev_##lvl(__nn->dp.dev, "ctrl: " fmt, ##__VA_ARGS__); \ +}) + +#define nn_err(nn, fmt, ...) nn_pr(nn, err, fmt, ##__VA_ARGS__) +#define nn_warn(nn, fmt, ...) nn_pr(nn, warn, fmt, ##__VA_ARGS__) +#define nn_info(nn, fmt, ...) nn_pr(nn, info, fmt, ##__VA_ARGS__) +#define nn_dbg(nn, fmt, ...) nn_pr(nn, dbg, fmt, ##__VA_ARGS__) + +#define nn_dp_warn(dp, fmt, ...) \ +({ \ + struct nfp_net_dp *__dp = (dp); \ \ - if (unlikely(net_ratelimit())) { \ - if (__dp->netdev) \ - netdev_warn(__dp->netdev, fmt, ## args); \ - else \ - dev_warn(__dp->dev, fmt, ## args); \ - } \ - }) + if (unlikely(net_ratelimit())) { \ + if (__dp->netdev) \ + netdev_warn(__dp->netdev, fmt, ##__VA_ARGS__); \ + else \ + dev_warn(__dp->dev, fmt, ##__VA_ARGS__); \ + } \ +}) /* Max time to wait for NFP to respond on updates (in seconds) */ #define NFP_NET_POLL_TIMEOUT 5
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