> -----Original Message----- > From: Li Li <[email protected]> > Sent: Monday, January 5, 2026 8:49 AM > To: Loktionov, Aleksandr <[email protected]> > Cc: Nguyen, Anthony L <[email protected]>; Kitszel, > Przemyslaw <[email protected]>; David S. Miller > <[email protected]>; Jakub Kicinski <[email protected]>; Eric Dumazet > <[email protected]>; [email protected]; > [email protected]; [email protected]; David Decotigny > <[email protected]>; Singhai, Anjali <[email protected]>; > Samudrala, Sridhar <[email protected]>; Brian Vazquez > <[email protected]>; Tantilov, Emil S <[email protected]> > Subject: Re: [Intel-wired-lan] [PATCH v2] idpf: increment completion > queue next_to_clean in sw marker wait routine > > On Sun, Jan 4, 2026 at 11:43 PM Loktionov, Aleksandr > <[email protected]> wrote: > > > > > > > > > > > > From: Li Li <[email protected]> > > Sent: Monday, January 5, 2026 8:39 AM > > To: Loktionov, Aleksandr <[email protected]> > > Cc: Nguyen, Anthony L <[email protected]>; Kitszel, > > Przemyslaw <[email protected]>; David S. Miller > > <[email protected]>; Jakub Kicinski <[email protected]>; Eric > Dumazet > > <[email protected]>; [email protected]; > > [email protected]; [email protected]; David > Decotigny > > <[email protected]>; Singhai, Anjali <[email protected]>; > > Samudrala, Sridhar <[email protected]>; Brian Vazquez > > <[email protected]>; Tantilov, Emil S <[email protected]> > > Subject: Re: [Intel-wired-lan] [PATCH v2] idpf: increment completion > > queue next_to_clean in sw marker wait routine > > > > > > > > > > > > > > > > On Sun, Jan 4, 2026 at 11:19 PM Loktionov, Aleksandr > <[email protected]> wrote: > > > > > > > > > -----Original Message----- > > > From: Intel-wired-lan <[email protected]> On > Behalf > > > Of Li Li via Intel-wired-lan > > > Sent: Monday, January 5, 2026 7:47 AM > > > To: Nguyen, Anthony L <[email protected]>; Kitszel, > > > Przemyslaw <[email protected]>; David S. Miller > > > <[email protected]>; Jakub Kicinski <[email protected]>; Eric > > > Dumazet <[email protected]>; [email protected] > > > Cc: [email protected]; [email protected]; David > > > Decotigny <[email protected]>; Singhai, Anjali > > > <[email protected]>; Samudrala, Sridhar > > > <[email protected]>; Brian Vazquez <[email protected]>; > > > Tantilov, Emil S <[email protected]>; Li Li > > > <[email protected]> > > > Subject: [Intel-wired-lan] [PATCH v2] idpf: increment completion > > > queue next_to_clean in sw marker wait routine > > > > > > Currently, in idpf_wait_for_sw_marker_completion(), when an > > > IDPF_TXD_COMPLT_SW_MARKER packet is found, the routine breaks out > of > > > the for loop and does not increment the next_to_clean counter. > This > > > causes the subsequent NAPI polls to run into the same > > > IDPF_TXD_COMPLT_SW_MARKER packet again and print out the > following: > > > > > > [ 23.261341] idpf 0000:05:00.0 eth1: Unknown TX completion > type: > > > 5 > > > > > > Instead, we should increment next_to_clean regardless when an > > > IDPF_TXD_COMPLT_SW_MARKER packet is found. > > > > > > Tested: with the patch applied, we do not see the errors above > from > > > NAPI polls anymore. > > > > > > Signed-off-by: Li Li <[email protected]> > > > --- > > > Changes in v2: > > > - Initialize idpf_tx_queue *target to NULL to suppress the > "'target' > > > uninitialized when 'if' statement is true warning". > > > > > > drivers/net/ethernet/intel/idpf/idpf_txrx.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c > > > b/drivers/net/ethernet/intel/idpf/idpf_txrx.c > > > index 69bab7187e541..452d0a9e83a4f 100644 > > > --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c > > > +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c > > > @@ -2326,7 +2326,7 @@ void > idpf_wait_for_sw_marker_completion(const > > > struct idpf_tx_queue *txq) > > > > > > do { > > > struct idpf_splitq_4b_tx_compl_desc *tx_desc; > > > - struct idpf_tx_queue *target; > > > + struct idpf_tx_queue *target = NULL; > > Linux kernel is against premature initialization just to silence a > compiler. > > The target variable is dereferenced at idpf_queue_clear(SW_MARKER, > > target)) but can remain uninitialized if execution jumps to the > next: > > label via a goto before target is assigned. > > Isn't it? > > > > That is correct. When the following if statement (line 2341-2343) > evaluates to true: > > > > > > > > if (FIELD_GET(IDPF_TXD_COMPLQ_COMPL_TYPE_M, ctype_gen) != > > IDPF_TXD_COMPLT_SW_MARKER) > > goto next; > > > > > > > > Then the initialization at line 2346: > > > > > > > > target = complq->txq_grp->txqs[id]; > > > > > > > > would be skipped, making "target" uninitialized. > > > > > > > > Therefore, in this patch, I need to initialize "target" to NULL. > > > > > > > > The ‘NULL’ target variable can be dereferenced at > idpf_queue_clear(SW_MARKER, target)), isn’t it? > > That would not be possible, because right before > "idpf_queue_clear(SW_MARKER, target))", "target" > is initialized to "complq->txq_grp->txqs[id]": > > if (FIELD_GET(IDPF_TXD_COMPLQ_COMPL_TYPE_M, ctype_gen) != > IDPF_TXD_COMPLT_SW_MARKER) > goto next; > > id = FIELD_GET(IDPF_TXD_COMPLQ_QID_M, ctype_gen); > target = complq->txq_grp->txqs[id]; > > idpf_queue_clear(SW_MARKER, target); > > "target" only remains uninitialized if the if statement above > evaluates to true and skips the initialization. > > > > > > > > > > > > > > > > u32 ctype_gen, id; > > > > > > tx_desc = flow ? &complq->comp[ntc].common : > > > @@ -2346,14 +2346,14 @@ void > > > idpf_wait_for_sw_marker_completion(const > > > struct idpf_tx_queue *txq) > > > target = complq->txq_grp->txqs[id]; > > > > > > idpf_queue_clear(SW_MARKER, target); > > > - if (target == txq) > > > - break; > > > > > > next: > > > if (unlikely(++ntc == complq->desc_count)) { > > > ntc = 0; > > > gen_flag = !gen_flag; > > > } > > > + if (target == txq) > > Are tou sure that incremented ntc value is ever written back to > complq->next_to_clean? > > > > > > > > Yes, the value of "ntc" is written back to "complq->next_to_clean" > at > > the end of the function > > > > (at line 2360): > > > > > > > > complq->next_to_clean = ntc; > > > > Thank you, I don’t see it from the patch. > > > > > > > > > > > + break; > > > } while (time_before(jiffies, timeout)); > > > > > > idpf_queue_assign(GEN_CHK, complq, gen_flag); > > > -- > > > 2.52.0.351.gbe84eed79e-goog
Thank you for the clarifications Reviewed-by: Aleksandr Loktionov <[email protected]>
